Briefly

The New York Stock Exchange, in its quarterly review of “circuit breakers,” on Friday set the fourth-quarter level for a trading halt in U.S. stock markets at a drop of 900 points in the Dow Jones industrial average. That’s down from the previous level of 1,100 in the third quarter. Point levels are set quarterly by using the average closing level of the Dow for the previous month. . . . The Securities and Exchange Commission on Friday extended for two more weeks emergency rules that give companies more latitude in buying back their own shares. The rules are designed to help stabilize the stock market.