On 15 October, foreign institutional investors (FIIs) were net sellers of Indian stocks for the 15th session in a row. Each evening the provisional figure came out red, and the same question followed: is the market about to fall?

I wanted to answer that with data instead of vibes, so I wrote a small backtest: find every long FII selling streak since 2014, and check what the Nifty 50 did afterwards. The whole thing is 58 lines of Python. This post walks through how it works and the three traps I hit. The findings, with charts and caveats, are in the companion piece on Medium (linked at the end).

The short answer: after day 10 of a selling streak, the Nifty did about what it does after any random day.

Not investment advice. I built the data API used here.…