Stop tape watching

Ben Brostoff
Dec 13, 2018 · 2 min read

There are things we cannot affect the outcome of.

As someone who dabbles in both Daily Fantasy Sports and trading equities and options, I have seen firsthand how useless it is to “tape watch”. What this means is watching an asset’s price in real time with no intent to act on or usefully leverage the information.

Delete this app from your phone if you’re a long-term investor.

It’s fine to check in on an asset price if it’s to throw it in a spreadsheet or figure out how to automate extraction or to just do anything useful with it. Simply watching it, however, is always going to do more harm than good.

Let’s use DFS to create an example. After pain-staking research and last minute lineup changes to account for injuries and other game time factors, you enter a highly-calculated dollar amount in carefully selected contests to be consistent with the Kelly criterion and your contest exposure strategy.

Then the games start.

At this point, there is nothing you can do to affect your IRR. Let me stress this point, mainly for myself — there is nothing you can do to affect your IRR for that day once the games start.

In fact, checking in on the games (let’s call it the market to be general) hurts your future IRR at worst and does nothing at best. It’s time you could’ve spent researching new assets or developing a new strategy. The market does not care whether you observe it or not; the outcome is not impacted by the act of observation.

If you check in, you’re receiving incomplete data that could widen the gap between reality and your mental model of the world. Players routinely have monster quarters followed by duds; stocks routinely have monster quarters and then go to zero; all assets behave differently over long periods of time than short, “tape-watching” periods of time.

Stop watching the tape. If you do, you’re destroying opportunities to enhance future returns and confusing yourself by observing meaningless data.

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Written by

Software engineer. GitHub: https://github.com/BenBrostoff , Blog: http://benbrostoff.github.io/

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