* European banks borrow more than expected from ECB
* Second estimate on 4th-qtr U.S. GDP on tap
* Futures up: Dow 33 pts, S&P 2.5 pts, Nasdaq 1.75 pts
NEW YORK, Feb 29 (Reuters) - U.S. stock index futures edged up on Wednesday after European banks absorbed more than half a trillion euros as part of an effort to stabilize the euro zone's financial system.
* The U.S. stock market is seen adding to the previous day's gains that catapulted the Dow industrials and the S&P 500 above key levels to close at multi-year highs.
* Banks grabbed 530 billion euros at the European Central Bank's second offering of low-cost three-year loans, fueling hopes that more credit will flow to businesses and government borrowing costs will ease further. The borrowings topped expectations.
* S&P 500 futures rose 2.5 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration of the contract. Dow Jones industrial average futures gained 33 points, and Nasdaq 100 futures added 1.75 points.
* The Dow closed above 13,000 for the first time since May 2008 on Tuesday, while the S&P ended above 1,370, its May 2011 intraday high, which could entice money managers seeking to boost returns. But some analysts warned this year's rally has come in light volume, and further gains could trigger selling.
* Daily volume on the New York Stock Exchange, NYSE Amex and Nasdaq has averaged 6.87 billion shares in February. The average in February 2011 was 7.81 billion.
* Economic data will be in focus, with the second estimate on fourth quarter U.S. gross domestic product expected at 8:30 a.m. EST (1330 GMT), and February Chicago PMI at 9:45 a.m. EST (1445 GMT).
* For GDP, economists in a Reuters survey forecast a 2.8 percent annualized pace of growth, a repeat of the first fourth-quarter increase estimate. For PMI, economists see a reading of 61.5, compared with 60.2 in January.