Stock buybacks are falling to a three-year low just as U.S. chief executive officers boost spending on plants and equipment to a record.

Companies announced $1.1 billion of repurchases a day on average during the earnings season in April and May, the lowest level since mid-2009, according to data compiled by Bloomberg and TrimTabs Investment Research Inc. Capital spending in the U.S. has risen since 2010 and reached $63.6 billion in March. Devon Energy Corp. eliminated buybacks and boosted exploration and production spending 18 percent. United Parcel Service Inc. cut repurchases in order to buy TNT Express NV.

After the biggest first-quarter gain for the Standard & Poor's 500 Index since 1998, bears say the 58 percent decline in buybacks removes key support for equities amid Europe's debt crisis and a weakening U.S. recovery. While orders for capital equipment fell last month, bulls say the two-year gain in business investment shows CEOs are growing more optimistic, spending to raise profits instead of reducing stock to boost per-share earnings.