Dead stock is the share of your inventory with no sales in the last 90 days or more.
Why it is worse than it appears
Dead stock shows on your balance sheet as an asset at what you paid for it, which is almost never what it is worth.
An item that has not moved in three months is unlikely to move in the next three, and it is competing for shelf space, working capital and attention against items that do sell. The value on paper is a number nobody has revisited since the day it was bought.
Where it comes from
Rarely a bad decision. Usually a change nobody adjusted for: a model superseded, a supplier switched, a service line dropped, a bulk discount taken on something that turned out to sell more slowly than expected.
The bulk discount is the one worth naming. Buying twelve to save 15% is a good deal if you sell twelve. If you sell four and hold eight for two years, it was a loan to your supplier at a bad rate.
What to do about it
The options are limited and all of them are better than waiting.
Sell it below cost. Recovering half of something beats holding all of nothing, and the loss happened at purchase rather than at sale.
Use it. Bundle it into jobs where it fits, even at no margin.
Return it, if the supplier will take it. Worth asking.
Write it off. Not defeat — it makes the balance sheet true and stops the item consuming attention.
The habit
Review anything past 90 days quarterly, and decide. The cost of dead stock is not the initial purchase, which is already spent. It is the years it sits there while the decision goes unmade.
Available where inventory tracking is enabled for your workspace.