Companies in the Standard & Poor's 500 Index really lovetheir shareholders. Maybe too much.

They're poised to spend US$914 billion on share buybacks anddividends this year, or about 95 percent of earnings, data compiledby Bloomberg and S&P Dow Jones Indices show. Money returned tostock owners exceeded profits in the first quarter and may again inthe third. The proportion of cash flow used for repurchases hasalmost doubled over the last decade while it's slipped for capitalinvestments, according to Jonathan Glionna, head of U.S. equitystrategy research at Barclays Plc.

Buybacks have helped fuel one of the strongest rallies of thepast 50 years as stocks with the most repurchases gained more than300 percent since March 2009. Now, with returns slowing, investorssay executives risk snuffing out the bull market unless they startplowing money into their businesses.