US stock exchanges have proposed to overhaul the way trading resumes after a halt caused by wild price swings, advancing a new system that could reduce the number of trading pauses but lengthen how long they last.

The revisions are designed to respond to problems exposed by a market rout on August 24, 2015, when safeguards intended to limit extreme volatility were blamed for exacerbating the market turmoil. The changes, which the Securities and Exchange Commission must approve, could be implemented by early next year.