We thought we’d found a stock-market signal.
Then we discovered the market was getting there before the news.
The stats were right. Our interpretation wasn’t.
A cautionary story about AI, earnings, backtests, and look-ahead bias:
tommijohnsen.substack.com/p/the-market...
tommijohnsen.substack.com
The Market Reads the Announcement. By the Time It’s News, It’s Old.
Since August we’ve reported one finding we were confident in: when a company gets plenty of news coverage in a day, stocks with good news beat stocks with bad news the next day by a small but reliable...