Value notes
How long is a drop alert's value good for?
The value in a drop is the gap between your book's price and the new fair price. It lasts until your book reprices, so measure your own decay.
A drop alert tells you a price fell and hands you the fair price after the fall. The value in that alert is the gap between the fair price and what your book still offers, and the question every recipient eventually asks is how long that gap survives. There is no fixed answer in minutes. The gap lasts until your book reprices, and your book reprices at its own speed. What you can do is measure that speed and set your freshness window from the result.
What actually decays
The alert itself does not decay. The prices in it were true the moment they were sent, and the attached no-vig fair price stays what it was: the market's view at the second of the move. What decays is the opportunity, the distance between that fair price and the price you can still get.
The reason is the follow-through. When the sharpest line falls, other books copy the move, and each copy narrows the gap your alert reported. Your book is somewhere in that queue. If it tends to reprice in two minutes, the alert's value has a two-minute life. If it lags for an hour on a minor league, the same alert is still live long after it arrived.
Measure the decay from your own log
You already have the instrument. Each alert carries the old price, the new price and the fair price; your book's offer is the only missing field. For a couple of weeks, log every alert you care about and snapshot your book's price on that side at fixed marks: at the alert, then one, five, fifteen and sixty minutes after.
Then grade each snapshot the same way. The EV calculator prices any offer against the fair line: its worked example puts Pinnacle 2.10, fair 2.17 and your price 2.25 at an EV of +3.80%, as the calculator page shows, checked 2026-10-23. Run that comparison for every snapshot. The output is a decay table: the share of alerts still offering positive EV at each mark.
That table is your answer. If half the value is gone by five minutes, your window is five minutes. If most of it survives the hour on the markets you follow, you can afford to be deliberate.
Why the clock runs at different speeds
Expect the table to split. High-volume leagues attract fast copying; thin leagues let the gap sit. Early prematch moves travel slowly because there is time and no urgency; moves near the close get copied quickly because every book is watching the same screen.
The size of the drop plays a role as well. The feed measures a drop as the fall divided by the old price, so 2.37 to 2.25 is a 5.06% drop, the same arithmetic the dropping odds calculator applies, checked 2026-10-23. A small drop barely over your threshold invites little copying and the gap can linger. A large, loud drop announces itself to every book at once.
Split your decay table by league and by time to the start before you read too much into the average.
Setting your freshness window
Once the table exists, the rule writes itself. Pick the mark where the surviving value stops justifying the work, and treat anything older as information, not an invitation. Late alerts still earn their place in the log: they tell you the market moved, which colors how you read the next alert on the same match.
Revisit the table every month or two. Books change how fast they follow, your alert mix shifts with the season, and a window that was honest in the summer can be sloppy by autumn.
A drop alert is freshest at the second it arrives, but freshest is not the same as finished. Measure the decay, set the window, and let the log decide what late means.