WASHINGTON — Four years into a sluggish recovery marked by modest hiring, the economic horizon looks pretty much the same in the eyes of the nation’s top corporate bosses.

The latest quarterly survey by the Business Roundtable, representing chief executives of major companies, found just a slight improvement in the outlook for economic activity in the next six months, with a small pickup in sales and hiring.

The results released Wednesday “reflect an economy on the slow road to recovery,” said Jim McNerney, CEO of Boeing Co. and chairman of Business Roundtable. The survey was completed by 141 CEOs in the second half of May.

Business Roundtable said 32 percent of these CEOs expected an increase in U.S. employment at their companies in the next six months, up from 29 percent in the first quarter. But 26 percent forecast a decrease, and that’s up 1 percentage point from three months earlier. The rest see no change in employment.

Business Roundtable member companies are among the largest in America and, combined, employ about 16 million people.