The Short-Sale Restriction (SSR) — sometimes called the alternate uptick rule — triggers when a stock falls 10% or more from the prior day's close. Once active, short sellers can only execute on an upstep (above the current best bid), not by hitting the bid. It stays in effect for the rest of that day and the next.

Why it exists

SSR is a circuit-breaker-style rule designed to prevent short sellers from piling on and accelerating a decline in an already-falling stock. By forcing shorts to wait for an uptick, it removes some of the aggressive downward pressure that can turn a drop into a cascade.

How it changes behavior

When SSR is on, shorts can't aggressively hit the bid to press a stock lower — they have to be more passive. This often reduces downside velocity and can make sharp bounces more likely, since one side of the aggressive selling is constrained. Traders watch for the SSR flag because it subtly shifts the intraday dynamics of a beaten-down name.

SSR doesn't stop shorting — it just takes away the sellers' ability to slam the bid.

The practical read

For a trader, SSR is context: a stock down 10%+ with the restriction on may see dampened downside momentum and springier bounces than the raw chart suggests. It's one more piece of market plumbing — like order routing and halts — that shapes how price moves beneath the surface.