Updated

U.S. chief executives have grown more optimistic about economic growth this year, and more of them plan to boost spending and hiring within the next six months.

The Business Roundtable says its CEO outlook index rose to 92.1 in the first quarter of this year, the highest level in two years. The index measures chief executives' expectations for sales, investment spending and hiring.

The biggest improvement occurred in investment spending. Nearly half the CEOs surveyed said they plan to invest more in the next six months, up from 39 percent last quarter. Such spending is typically followed by more hiring as companies expand.

Randall Stephenson, CEO of AT&T, attributed the better outlook to more stability and certainty surrounding tax and spending policies in Washington.