* Futures: S&P 5 pts, Nasdaq 0.75 pts, Dow 22 pts
By Sruthi Shankar
Dec 21 (Reuters) - A long-promised bill to slash corporate taxes passed the U.S. Congress but failed to excite Wall Street on Thursday, as investors appeared to lock in gains after a record rally this year in anticipation of the bill.
Futures on the Dow and the Nasdaq indicated a flat opening, while S&P 500 futures were up 0.17 percent on Thursday.
The three main stock indexes dipped on Wednesday after both houses of Congress approved the bill, which includes cutting corporate tax rate to 21 percent from 35 percent. Lower taxes will boost company earnings and potentially lead to higher dividends and increased stock buybacks.
It was uncertain when the bill would be signed by President Donald Trump as the House is set to vote on a funding plan to avert a government shutdown by weekend.
The S&P 500 has risen by about 20 percent this year, its best performance since 2013, partly driven by hopes of tax cuts.
A bunch of companies including AT&T, Wells Fargo and Boeing promised higher pay for workers or more investment in training. Some others have forecast a rise in earnings due to tax cuts.
At 6:50 a.m. ET (1150 GMT), S&P 500 e-minis were up 5 points, or 0.19 percent, with 105 contracts changing hands.
Nasdaq 100 e-minis were up 0.75 points, or 0.01 percent, in volume of 25 contracts.
Dow e-minis were up 22 points, or 0.09 percent, with 4 contracts changing hands.
In economic data, the Commerce Department's final estimate of third-quarter gross domestic product is expected to show the economy grew at a 3.3 percent annualized rate, in line with expectations.
Weekly initial claims for state unemployment benefits are forecast to have increased to 231,000 for the last week from 225,000 in the previous week. Both reports are due at 8:30 a.m. ET.
Among early movers, Bed Bath and Beyond fell more than 4 percent after the company said comparable sales fell 0.3 percent in the third quarter.
Accenture gained 2.2 percent after the consulting and outsourcing services provider reported strong quarterly profit, driven by digital and cloud services business.
U.S.-listed shares of Aeterna Zentaris soared about 70 percent after the U.S. FDA approved the Canadian drugmaker' s oral test to diagnose adult growth hormone deficiency. (Reporting by Sruthi Shankar in Bengaluru)