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Code examples, market analysis, and data quality deep-dives.

Which Sectors Lead Out of a Market Bottom? Sector Recovery Analysis in Python
Are Buybacks Funded by Cash Flow or by Debt? S&P 500 Payout Analysis in Python
What to Look for in Fundamentals Data
Does Cash on the Balance Sheet Cushion a Crash? Quintile Sorts in Python
Do Corporate Insiders Time the Market? S&P 500 Insider Buying Breadth in Python
Does Unstable Volatility Warn of Deeper Drawdowns? Vol-of-Vol Sorts in Python
Does Fast Asset Growth Predict Weak Stock Returns? Decile Sorts in Python
How to Replace yfinance in a Python Script
Does the Nasdaq-100 Index Effect Still Exist? Event Study in Python
Does the Piotroski F-Score Still Work? Quality Screening in Python
How Many S&P 500 Stocks Beat the Index? Return Breadth Analysis in Python
Why Beta Differs Between Data Sources
Where to Get Historical Dividend Data for Stocks
Does a High Dividend Yield Predict a Dividend Cut? Yield-Trap Screening in Python
Do Old Ticker Symbols Still Point to the Same Company? S&P 500 Ticker Recycling in Python
What Growth Is Priced Into the S&P 500? Reverse DCF in Python
Ticker vs CIK vs FIGI: Which Company ID to Use
Does Illiquidity Still Pay? Amihud Measure in the S&P 500 in Python
Where to Get R&D Spending Data for Public Companies
Does R&D Spending Predict Revenue Growth? Cross-Sectional Test in Python
What Actually Drives Return on Equity? DuPont Decomposition in Python
What Data Do You Need to Measure Portfolio Risk?
Does a 60/40 Portfolio Actually Cut Drawdowns? Stocks and Bonds in Python
Do Steady Margins Mean Calmer Stocks? Cross-Sectional Analysis in Python
Do Sectors Diversify When It Matters? Conditional Correlation in Python
How to Get Historical Market Cap Data in Python
How Much of the S&P 500 Survives 20 Years? Index Turnover Analysis in Python
Does Joining the S&P 500 Bring New Institutional Owners? 13F Event Study in Python
Is Volatility Seasonal? Calendar Month Analysis of Realized Volatility in Python
Does Fast Revenue Growth Force Companies to Borrow? Cash Funding Analysis in Python
How Far Back Does SEC EDGAR Data Go?
Are One-Time Charges Really One-Time? Charge Frequency Analysis in Python
Does Buying the Dip Work? Short-Term Reversal by Volatility Regime in Python
Alpha Vantage vs Massive vs xfinlink for Fundamentals
How Long Does a Stock Take to Recover From a 50% Fall? Drawdown Analysis in Python
Do Companies That Shrink Their Share Count Outperform? Net Buyback Yield in Python
How Much Does the Dow's Price Weighting Distort It? Index Weighting Analysis in Python
How to Get SEC Form 4 Insider Trading Data in Python
Can Anything Predict Next Month's Stock Returns? Out-of-Sample R-Squared Testing in Python
How Much of a Stock's Return Comes From Its Sector? Variance Decomposition in Python
Altman Z-Score: Where To Get It in Python
Do Value Screens Agree on Which Stocks Are Cheap? Multiple Overlap Analysis in Python
Annual vs Quarterly Financial Data: Which to Use
Do High Returns on Capital Persist? ROIC Fade Analysis in Python
Does Past Beta Predict Future Beta? Beta Stability Testing in Python
Do Defensive Sectors Actually Defend? Up and Down Capture in Python
How to Choose a Financial Data API
Do Small Caps Actually Beat Large Caps? Size Premium Test in Python
What If You Miss the Market's Best Days? Extreme-Day Analysis in Python
Does Rebalancing Add Return? Fixed-Weight vs Drift Portfolios in Python
Which S&P 500 Companies Are Closest to Default? Merton Distance-to-Default in Python
What Happens to Stocks Removed From the S&P 500? Replacement Pair Analysis in Python
Does the Golden Cross Work? 50/200 Moving Average Crossover Backtest in Python
Financial Data for Academic Finance Research
Does Skipping the Most Recent Month Improve Momentum? S&P 500 Decile Sorts in Python
Does Cointegration Survive Out of Sample? Pairs Trading Validation in Python
Which Dividends Are Not Covered by Cash? Free-Cash-Flow Coverage Screening in Python
GICS vs SIC vs NAICS: Which Industry Classification to Use
How Many Stocks Does It Take to Diversify? Random Portfolio Simulation in Python
How Many Days of Data Does a Volatility Estimate Need? Range-Based Estimators in Python
How Much of S&P 500 Cash Flow Is Stock Compensation? Cross-Sectional Analysis in Python
What Is a 13F Filing? Institutional Holdings Explained
Does Revenue Growth Explain Profit Growth? Cross-Sectional Decomposition in Python
How Much of the Nasdaq 100 Is Already in the S&P 500? Index Overlap Analysis in Python
How Often Does a 99% Value-at-Risk Limit Actually Break? VaR Backtesting in Python
Real-Time vs End-of-Day Market Data: Which Do You Need?
How Concentrated Are S&P 500 Earnings? Point-in-Time Index Analysis in Python
Does Volatility Scale With the Square Root of Time? Variance Ratio Test in Python
Does Goodwill Distort the Price-to-Book Screen? Goodwill-Adjusted Valuation in Python
How Are Shares Outstanding Reported (and Why They Disagree)
Do Low-Volatility Stocks Deliver Better Risk-Adjusted Returns? S&P 500 Quintile Sorts in Python
Does Trend Following Beat Buy and Hold? Time-Series Momentum in Python
Has the Stock-Bond Correlation Flipped? 60/40 Portfolio Risk in Python
What API to Use for a Stock Screener
Which Assets Hedge Inflation Shocks? Macro Factor Betas in Python
Does Covariance Shrinkage Beat the Sample Covariance? Minimum-Variance Portfolios in Python
Do Faster Inventory Turns Mean Thinner Margins? Gross Margin Return on Inventory in Python
SEC EDGAR API vs Fundamentals API: Which to Use
Does Fast Earnings Growth Persist? Rank Correlation Analysis in Python
Split Adjustment Explained: Adjusted Close vs Close
Which Trading Day of the Month Pays Best? Turn-of-the-Month Analysis in Python
Can You Use Yahoo Finance Data Commercially?
How Many Independent Bets Does a Nine-Sector Portfolio Give You? Eigenvalue Analysis in Python
Which Volatility Forecast Wins One Month Ahead? HAR vs EWMA in Python
How Concentrated Are Institutional Equity Portfolios? Form 13F Concentration Analysis in Python
Do Stocks Earn Their Returns Overnight or Intraday? Return Decomposition in Python
When Do Corporate Insiders Actually Trade? Form 4 Timing Analysis in Python
Data Requirements for Backtesting a Trading Strategy
What Is Survivorship Bias in Backtesting?
Do High Dividend Yields Come From Bigger Payouts or Falling Prices? Yield Decomposition in Python
Do Stocks Fall Harder Than They Rise? Downside Beta vs Upside Beta in Python
Does Volatility Targeting Improve Sharpe Ratios? Seven-Asset Backtest in Python
Free Stock Market Data APIs: What You Actually Get
How to Give an LLM Financial Data With an MCP Server
Does Post-Earnings Announcement Drift Survive Real Filing Dates? PEAD Event Study in Python
Do Insider Buying Clusters Predict Returns? Signal Testing in Python
Does the S&P 500 Index Effect Still Exist? Event Study in Python
Are Companies Leaving the S&P 500 Faster Than They Used To? Index Survival Analysis in Python
Does Gross Profitability Predict Stock Returns? Quintile Factor Test in Python
What Growth Rate Is the Market Pricing In? Reverse DCF in Python
Does a Strong Balance Sheet Cushion Drawdowns? Leverage and Downside Risk in Python
Does Ticker Recycling Corrupt a Mean-Reversion Backtest? Entity-Resolved Z-Scores in Python
How Much of a Growth Screen's Backtested Edge Is Survivorship Bias? Point-in-Time Index Testing in Python
Why Do Leveraged ETFs Decay? Measuring Volatility Drag in Python
Are Consumer Staples Margins Shrinking Under Inflation? Gross Margin Trend Analysis in Python
Do Weak Jobs Reports Predict Market Drawdowns? NFP Surprise Event Study in Python
Is the Rotation From Tech to Industrials Backed by Earnings? Relative EPS Growth Analysis in Python
Is the Semiconductor Rally Broadening Beyond NVIDIA? Return Dispersion Analysis in Python
Which Stocks Benefit Most When Oil Prices Fall? Oil Beta Screening in Python
Do Bond Returns Predict Stock Returns? Granger Causality Test in Python
Which Stocks Actually Drive Portfolio Returns? Shapley Value Attribution in Python
Does "Sell in May" Still Work? Calendar Anomaly Backtest in Python
How to Build Complete Price History Through Ticker Changes? Entity Resolution in Python
Are KO and PEP Cointegrated? Pairs Trading Signal Construction in Python
Which Commodities Have the Strongest Momentum? Rotation Backtest in Python
Which Commodity ETFs Have the Worst Tail Risk? Expected Shortfall in Python
Are Gold Miners Leveraged Gold Bets? Rolling Beta Analysis in Python
Does the Base-Metals-to-Gold Ratio Lead Cyclical Stocks? Signal Test in Python
Can Risk Parity Tame Commodity Volatility? Portfolio Optimization in Python
Are Power Stocks Becoming an AI Infrastructure Trade? Momentum Screening in Python
Which AI Chip Stocks Have Margin Momentum? Profitability Trend Analysis in Python
Which AI Stocks Are Cheapest Relative to Growth? Growth-Adjusted Valuation in Python
Does AI Stock Leadership Persist? Momentum Backtest in Python
Which AI Stocks Have the Cleanest Balance Sheets? Net Cash Screening in Python
Can Risk Parity Reduce Mega-Cap Drawdowns? Portfolio Optimization in Python
Which Growth Stocks Are Self-Funding? Cash-Flow Quality Screening in Python
Which Sectors Struggle When the Dollar Rallies? Sector Rotation Analysis in Python
Do Cheap Stocks Hold Up When Bonds Sell Off? Valuation Rotation in Python
Does the Nasdaq 100 Have Better Growth Quality Than the Dow? Index Constituent Analysis in Python
Do Healthcare Cash-Flow Margins Predict Returns? Signal Evaluation in Python
Which Dividend Stocks Survive a Cash-Flow Stress Test? Dividend Screening in Python
Does Heavy Insider Selling Predict Weak Returns? Insider Flow Test in Python
Can Quality Screens Reduce Small-Cap Balance-Sheet Risk? Russell 2000 Test in Python
Which Retailers Have Positive Operating Leverage? Margin Screening in Python
Is MSTR a Leveraged Bitcoin Proxy? Rolling Beta Analysis in Python
Is Micron's Memory Cycle Recovering? Inventory and Margin Forecasting in Python
Which Sectors Work When Bonds Rally? Rate-Sensitive Rotation in Python
Do One-Month Price Extremes Reverse? Signal Evaluation in Python
Do Low-Volatility S&P 500 Stocks Reduce Drawdowns? Factor Test in Python
Is AI Capex Paying Back Fast Enough? Revenue Hurdle Forecasting in Python
Could Shorter AI Asset Lives Hit Earnings? Depreciation Stress Test in Python
How Much AI Capex Risk Can a Portfolio Remove? Constrained Optimization in Python
Is the AI Capex Trade Crowded? Rolling Volatility and Sector Rotation in Python
Did the AI Boom Come From Existing S&P 500 Members? Point-in-Time Momentum Test in Python
Is AI Revenue Circular? Customer-Vendor Capex Loop Analysis in Python
Is the AI Trade Connected to Private Credit? Rolling Correlation Network in Python
Is Apollo More Balance-Sheet Sensitive Than Peers? Leverage Screen in Python
Are AI Earnings Supported by Cash Flow? Accrual and Capex Screen in Python
Can Defensive Stocks Hedge AI Drawdowns? Basket Regime Test in Python
How Fast Does the Market Price In Fed Decisions? FOMC Event Study in Python
How Much Are Options Sellers Overpaid? The Variance Risk Premium in Python
Which Companies Have the Worst Earnings Quality? Sloan Accrual Screen with Geographic Revenue Data in Python
Does the Oil-to-Gold Ratio Signal Recessions? XLE/GLD Backtest in Python
Is AI Spending Crowding Out Free Cash Flow? Capex Sustainability Across the Mag 7 in Python
Does a Long Energy / Short Bonds Portfolio Capture Inflation Surprises? Factor Construction in Python
Can a Hidden Markov Model Detect Oil Market Regimes? HMM Analysis in Python
Do Grain Prices Predict Food Inflation? Granger Causality Test in Python
Does the Corporate Credit Spread Predict Stock Market Crashes? BAA-AAA Spread Analysis in Python
Do Oil Stocks Hedge Inflation? Rolling Beta Analysis in Python
Which Stocks Are Most Rate-Sensitive? Equity Duration via Bond Beta in Python
Which Companies Have the Highest Accrual Ratios? Earnings Quality Screening in Python
Is Alpha Persistent or Decaying? Rolling Sharpe Ratio Analysis in Python
Are Markets Trending or Mean-Reverting? Hurst Exponent Analysis in Python
Is Consumer Discretionary vs Staples a Leading Indicator? XLY/XLP Ratio Analysis in Python
Does Heavy Capex Predict Future Stock Returns? Capital Expenditure Analysis in Python
How to Estimate Cost of Equity Using CAPM in Python
Is Volatility Predictable? Testing for Volatility Clustering in Python
Which Industrials Are Overleveraged? Net Debt to EBITDA Screening in Python
GM Before and After Bankruptcy: Why Entity Resolution Matters for Financial Data
What Is Adjusted Beta? Merrill Lynch Beta Shrinkage in Python
How Good Is a Stock Pick? Information Ratio and Tracking Error in Python
Do Stock Returns Follow a Normal Distribution? Testing for Fat Tails in Python
Which Large Caps Have the Highest Free Cash Flow Yield? FCF Screening in Python
Which Sectors Won Over 5 Years? Sector Rotation Analysis in Python
How to Forecast Stock Volatility with GARCH Models in Python
Are Stock Prices Mean-Reverting? Augmented Dickey-Fuller Test in Python
How to Calculate CAPM Alpha and Beta with Regression in Python
How to Compare Sector Sharpe Ratios and Sortino Ratios in Python
DELL: Why Stitching Historical Price Data Together Is Wrong
How to Analyze Drawdown and Recovery for Bank Stocks in Python
How to Screen SaaS Stocks by Revenue Growth and Cash Flow in Python
How to Screen REITs by Dividend Yield and Valuation in Python
How Correlated Are the Magnificent 7? Intra-Group Correlation in Python
AAPL vs XOM: Do Individual Stocks Have Seasonal Patterns?
How to Rank Large-Cap Stocks by Momentum in Python
How to Build a Multi-Endpoint Financial Dashboard in Python
How to Compare Volatility Across Energy Stocks in Python
How to Screen Healthcare Stocks by Valuation in Python
How to Build a Sector Correlation Matrix for Portfolio Diversification in Python
How to Find Oversold and Overbought Stocks Using Z-Scores in Python
How to Measure Earnings Quality: Cash Flow vs Net Income in Python
How to Build a Multi-Factor Stock Screen in Python (Value + Momentum + Quality)
How to Build a Simple DCF Model for Any Stock in Python
How to Screen Tech Stocks by Revenue Growth in Python
How to Screen Stocks by Balance Sheet Health in Python
Is "Sell in May" Real? SPY Monthly Seasonality Over 10 Years
How to Compare Sector Performance YTD Using Python
How to Screen Dividend Stocks by Yield and Quality in Python
How to Calculate Max Drawdown and Recovery Time for Any Stock in Python
How to Compare Profitability Across Mega-Cap Tech Stocks in Python
Why Ticker Symbols Are Unreliable: The Recycling Problem Every Quant Should Know
How to Calculate and Compare Stock Volatility in Python
How to Screen Blue-Chip Stocks by P/E Ratio in Python
How to Track Companies Through Ticker Changes, Bankruptcies, and Renames in Python
S&P 500 Turnover: How Much the Index Has Changed Since 2010
How to Calculate Stock Beta and Correlation in Python
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How to Replace yfinance in a Python Script

Swapping the import takes a minute. Getting the same numbers back takes an afternoon, because the two libraries disagree about what a column called close contains. As of August 2026, the yfinance documentation gives yf.download() the defaults auto_adjust=True and multi_level_index=True, so a multi-ticker call returns adjusted OHLC under a MultiIndex. xfl.prices() returns one long DataFrame in which close is the raw as-traded price, adj_close is split-adjusted, and return_daily is total return including dividends. Fix the column meanings first and the frame shape second; the rest of the migration is renaming.

What changes inside the DataFrame?

Three things move, and only one of them is cosmetic.

Adjustment stops being a hidden default. The yfinance reference documents auto_adjust as “Adjust all OHLC automatically? Default is True”, which means the price columns of a plain yf.download() are already modified before the script sees them. xfinlink splits that decision across separate columns rather than a flag: close is never modified, adj_close carries the split adjustment, and return_daily carries the total return that a performance calculation actually needs. A script that swaps the call, keeps reading close, and computes a percentage change will now step across every split in the sample.

The frame shape changes from wide to long. One xfl.prices(["AAPL", "MSFT"]) call returns rows, not nested columns, with ticker and entity_id as identifier columns beside the date. Anything written against a MultiIndex needs a pivot, which is one line, and anything written as a groupby gets simpler.

Corporate actions arrive in the same frame instead of separate attributes. yfinance documents actions=False as the download() default and exposes Ticker.dividends, Ticker.splits and Ticker.actions separately; xfinlink returns dividend and split_ratio as fields of the price frame, on the ex-date and the split date respectively.

Which call replaces which?

Every yfinance name below is a documented attribute or function in the yfinance reference as of August 2026.

yfinance xfinlink Note
yf.download(tickers, ...), Ticker.history() xfl.prices(tickers, start=, end=, interval=, fields=) Daily and coarser; interval accepts 1d through 1y
Ticker.dividends, Ticker.splits, Ticker.actions fields=["dividend", "split_ratio"] on xfl.prices() Same frame as the prices, no second call
Ticker.income_stmt, balance_sheet, cashflow and the quarterly variants xfl.fundamentals(ticker, period_type="annual") Built from SEC filings; annual statements reach 1950 on paid plans
Ticker.info xfl.metrics(ticker, fields=[...]) A typed DataFrame; categories include valuation, profitability, leverage and growth
Ticker.insider_transactions xfl.insiders(ticker, ...) Form 3, 4 and 5 transactions, one row each
Ticker.institutional_holders xfl.holdings(ticker, quarter="2026-03-31") Form 13F, one row per manager, security and quarter
No equivalent xfl.index("sp500", as_of="2015-06-30") Point-in-time constituents for sp500, ndx100, djia and russell2000
No equivalent xfl.resolve("META"), xfl.prices(entity_id=...) Company identity across ticker changes and ticker reuse

What does yfinance still cover that xfinlink does not?

Intraday bars, for one. The yfinance documentation lists intervals down to 1m with the caveat that “Intraday data cannot extend last 60 days”, which is enough for a short-horizon study and something xfinlink does not serve at all; daily is the finest interval on this side. Options chains through Ticker.option_chain, analyst estimates and revisions, fund holdings through funds_data, and a news feed are all documented yfinance attributes with no counterpart here.

There is also nothing to sign up for. The quick start in the yfinance documentation constructs yf.Ticker("MSFT") with no authentication step, while xfinlink wants a key on every call. For a weekend script that pulls one chart, that difference is real.

Those are different jobs from the one a daily research pipeline does. Nothing forces an all-or-nothing move either: an options call can stay where it is while the daily history moves.

How do you check the migration worked?

Two checks catch most of the damage, and a third confirms the frame shape. Run the first pair on a known split and on a large dividend payer, because those are the places where a column swap changes the answer without changing the shape of the output.

import xfinlink as xfl

xfl.set_api_key("YOUR_API_KEY")  # free at https://xfinlink.com/signup

px = xfl.prices("NVDA", start="2024-06-05", end="2024-06-12",
                fields=["close", "adj_close", "split_ratio"]).sort_values("date")
px["split_ratio"] = px["split_ratio"].fillna(1.0)
print(px[["date", "close", "adj_close", "split_ratio"]].to_string(index=False))

vz = xfl.prices("VZ", start="2021-08-02", end="2026-07-31",
                fields=["adj_close", "return_daily"]).sort_values("date")
price_return = vz["adj_close"].iloc[-1] / vz["adj_close"].iloc[0] - 1
total_return = (1 + vz["return_daily"].iloc[1:]).prod() - 1
print(f"\nVZ 2021-08-02 to 2026-07-31: price {price_return:.1%}, total {total_return:.1%}")

wide = (xfl.prices(["AAPL", "MSFT", "NVDA"], start="2024-06-05", end="2024-06-12",
                   fields=["adj_close"])
        .pivot(index="date", columns="ticker", values="adj_close"))
print("\n" + wide.to_string())
      date      close  adj_close  split_ratio
2024-06-05 1224.40002 122.440002          1.0
2024-06-06 1209.97998 120.997998          1.0
2024-06-07 1208.88000 120.888000          1.0
2024-06-10  121.79000 121.790000         10.0
2024-06-11  120.91000 120.910000          1.0
2024-06-12  125.20000 125.200000          1.0

VZ 2021-08-02 to 2026-07-31: price -16.1%, total 2.7%

ticker           AAPL       MSFT        NVDA
date
2024-06-05  195.87000  424.01001  122.440002
2024-06-06  194.48000  424.51999  120.997998
2024-06-07  196.89000  423.85001  120.888000
2024-06-10  193.12000  427.87000  121.790000
2024-06-11  207.14999  432.67999  120.910000
2024-06-12  213.07001  441.06000  125.200000

NVIDIA split 10-for-1 on 10 June 2024. The close column drops from 1208.88 to 121.79 across that date because that is what the stock traded at, while adj_close runs 120.888 to 121.790 without a step. If a migrated script shows a 90% single-day loss somewhere in 2024, it is reading close where it used to read an adjusted series.

Verizon is the second check. Over five years to 31 July 2026 the price fell 16.1% while the total return was positive 2.7%, so the sign of the answer depends entirely on which column the script reads. Dividend payers are where a quiet column mismatch turns into a wrong conclusion rather than a small error. The distinction is worked through in split adjustment explained and in where to get historical dividend data.

What can the script do after the swap?

Ticker strings stop being the primary key. xfl.resolve() returns a stable entity_id for each company that has used a ticker, along with its SEC CIK and its FIGI, and the price, statement, metric, insider and holdings functions each accept entity_id= in place of a ticker. That is what makes a company reachable after it renames itself, and what stops a study from picking up a different issuer that inherited the same three letters later. Delisted names stay reachable the same way, which is the usual reason a yfinance-era backtest reads too optimistic; survivorship bias in backtesting covers that case in full.

Universes gain a date. xfl.index("sp500", as_of="2015-06-30") returns the roster as it stood on that day rather than today’s members mapped backwards, so a screen run over history is not quietly restricted to the companies that survived to the present.

Statements, insider transactions and 13F holdings sit behind the same identifier as the prices, so a pipeline that already resolved a company does not need a second identity system to join filings to bars. An MCP server exposes the same functions to a language model when the eventual consumer is an assistant rather than a notebook; the setup is in the docs.

Start on the free key, which covers a rolling one-year window at 100 requests a day and one ticker per call. Paid plans lift both the history floor and the per-call ticker cap, and the current numbers are on the pricing page.

FAQ

Can both libraries live in the same project?
Yes. They are ordinary Python packages with no shared state. Keeping yfinance for an options chain while daily history comes from xfl.prices() is a normal setup.

What replaces auto_adjust=True?
Two columns instead of one flag: adj_close for a split-adjusted price series, return_daily for total return including dividends. Compound return_daily rather than differencing adj_close whenever dividends matter.

Is Yahoo Finance data usable in a commercial product?
The yfinance README states that the library “is intended for research and educational purposes” and that “the Yahoo! finance API is intended for personal use only”, and it points readers to Yahoo’s terms. The longer answer is in can you use Yahoo Finance data commercially.

How far back does the history go?
Daily prices reach 1996, financial statements 1950, and institutional holdings 1978 on paid plans. A free key sees a rolling twelve months of each.

Built with xfinlink — free financial data API for Python. pip install -U xfinlink

Built with xfinlink — free financial data API for Python. pip install -U xfinlink
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