* S&P 500 off more than 2 percent from record close
* Investors continue to watch geopolitical tensions
* ReneSola rallies in premarket after results
* Futures up: Dow 4 pts, S&P 1 pt, Nasdaq 1.5 pt (Adds biotech news, updates prices)
By Ryan Vlastelica
NEW YORK, Aug 12 U.S. stock index futures pointed to a flat open on Tuesday as uncertainty continued to swirl around the situation in Ukraine, even as many investors bet that it would not escalate dramatically.
* Equities have come under pressure because of the problems between Russia and Ukraine, with the S&P 500 at one point down about 4 percent from a record closing high in late July. The benchmark has recovered some of that decline, and has risen for the past two sessions, but it remains more than 2.5 percent below its record, suggesting traders may see bargains in the market.
* Futures were off their highs of the session amid ongoing concerns about the region, with Ukraine reporting that Russia had massed 45,000 troops on its border. Russia said a convoy of 280 trucks carrying humanitarian aid had set off for Ukraine, and Western governments warned against using help as a pretext for an invasion.
* Investors remained concerned about the fallout from any escalation in tensions. In Germany, geopolitical anxiety hit economic sentiment in August, the ZEW think tank said, with investor morale dropping to its lowest since December 2012. Market participants also monitored other areas of unrest, including the recent violence in the Gaza Strip and Israel and U.S. air strikes in Iraq.
* S&P 500 e-mini futures rose 1 point and were slightly above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average e-mini futures added 4 points, and Nasdaq 100 e-mini futures rose 1.5 point.
* Drug companies rallied in premarket trading. Intercept Pharmaceuticals Inc soared 49 percent to $352.13 a day after the company said its drug to treat liver disease was effective in mid-stage trials. Exact Sciences rose 5.9 percent to $18.10 before the bell after the Food and Drug Administration approved the company's noninvasive colorectal cancer screening test.
* ReneSola Ltd was one of the New York Stock Exchange's biggest premarket movers, jumping 4.6 percent to $2.97 after it reported a second-quarter swing to profit on lower costs.
* Consumer Reports magazine said Tesla Motors Inc's Model S sedan had "more than its share of problems" a year after giving the car top marks. Shares were little changed in premarket trading. (Editing by Jeffrey Benkoe and Nick Zieminski)