Data Done Wrong

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A quarter of a century ago, when I ran Prophet’s first advertisements, I used the headline “Data Done Right” to stress the importance of cleanness in our data. I must say, however, there’s something in the financial information industry which has had all those decades to get right but still hasn’t, and it’s these “after hours” pages big financial sites run.

Ostensibly, these are places where big after-hours moves, both up and down, are highlighted. They could be driven by earnings, corporate news, or anything else, and if the data was accurate, they would be interesting both after the market closed as well as in the morning before the open. The problem, though, is this………


The above, from MarketWatch, is just plain wrong. As pleased as I would be for Schwab to be down nearly 6%, for example, I assure you that it isn’t. Nor is BlackRock down over 6%. I haven’t checked each of the above, but I am confident based on experience that very little, if any, of this information is actually correct.

It isn’t any better at the Wall Street Journal.


I’ve got some experience in the wonderful world of financial data, and I can tell you that with some simple filtering, these pages could go from garbage to great. And yet, month after month, year after year, they have sucked out loud. I assume that very few people use them, or everyone knows not to the trust them, or that nobody cares.

If nothing else, please take it from your old pal Tim, these pages are chock full of absolutely erroneous information, so if you ever see something happening on them that makes your heart soar or sink, check it out on an actual trading terminal with real bid/ask data to see if there’s anything to it. Because there probably isn’t.

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