There are no routine restrictions on up and down price fluctuations of U.S. stocks in a single trading day. However, there could be Exchange and/or SEC imposed trading halts on individual stocks or market-wide trading halts.
Trading halts on specific symbols
Trading halts for specific symbols may be implemented for a number of reasons and can interrupt your orders to buy or sell particular securities. These stock-based halts are initiated by the specific stock exchange where the stock is listed or by the Securities and Exchange Commission.
During a trading halt, one or more securities exchanges will prevent all trades of the affected security. These halts typically last less than an hour but may be longer. Halts can occur multiple times in a single trading day or remain in place over multiple trading days. If a security is in a trading pause in the last 10 minutes of normal trading hours, the primary listing exchange will not reopen trading on that security until the next trading day. You can keep track of current and historical trading halts with both the NYSE and the Nasdaq websites.
Exchange Circuit Breakers
Market-wide trading halts can also be implemented by exchanges during periods of heightened volatility across the broader market.
Stock exchanges take measures to ease panic selling by invoking Rule 48 and halting trading when markets have severe downside movements. Under the 2012 rules, market-wide circuit breakers, or curbs, kick in when the S&P 500 index drops 7% for Level 1; 13% for Level 2; and 20% for Level 3 from the prior day’s close. A market decline that triggers a Level 1 or 2 circuit breaker before 3:25 pm EST will halt trading for 15 minutes, but will not halt trading at or after 3:25 p.m.
Level 1
7% market decline
Halt trading time - 15 minutes
Level 2
13% market decline
Halt trading time - 15 minutes
Level 3
20% market decline
Halt trading time - Close