Days to Cover

Days to cover converts a short position into a measure of how hard it would be to exit. Divide the reported short position, in shares, by the stock's average daily volume, usually over a 20 or 30 day window. A stock with 20 million shares short and 4 million shares traded a day has five days to cover: if short sellers were the only buyers, and volume held at its average, closing every position would take a full trading week.

The number is a liquidity ratio, not a forecast. It assumes short sellers account for all trading, which they never do, and that volume stays at its recent average, which it does not — volume typically spikes on exactly the days shorts are trying to exit. Treat it as a relative gauge: a stock at eight days to cover is a far more congested exit than one at half a day, whatever the absolute figures imply.

This is why it is a better crowding signal than short interest alone. A 4% short position in a heavily traded large-cap can be unwound in an afternoon. The same 4% in an illiquid small-cap may represent weeks of turnover, and it is that second case where a rally forces buying into a market with no sellers. High days to cover combined with high short interest is the classic squeeze setup.

Both inputs come with caveats on the ASX. The short position is the aggregated net figure ASIC publishes with a four trading day delay, so the numerator is stale by construction. Average daily volume can be distorted by index rebalance days, block crossings and takeover activity, any of which inflate the denominator and make the exit look easier than it is. Short-dated averages react quickly to those events; longer windows smooth them out.

Days to cover is also published under the name short interest ratio, particularly in US-sourced research. The two terms describe the same calculation, and both are used interchangeably in ASX commentary.