* Futures down: Dow 313 pts, S&P 37.25 pts, Nasdaq 90 pts
By Aastha Agnihotri
Feb 11 (Reuters) - U.S. stock index futures plunged on Thursday, with risk-averse investors piling into safe haven assets as another sharp fall in oil prices and cautious comments from Federal Reserve Chair Janet Yellen raised fresh doubts about the health of the economy.
* Yellen on Wednesday acknowledged tightening financial conditions and uncertainty about China and the risks that posed to the U.S. economy, but still kept open the possibility of further interest rate hikes.
* The dollar hit a 16-month low against the yen on Thursday as investors scrambled to buy gold and top-rated bonds and dumped stocks.
* Yellen, whose comments were taken to mean no near-term interest rate hikes, is scheduled to resume her testimony before Congress at 10:00 a.m ET (1500 GMT) on Thursday.
* A fresh reading on the U.S. labor market is due at 8:30 a.m. A report is expected show jobless claims fell to 281,000 last week.
* Wall Street, which had traded higher for much of the session after Yellen's comments on Wednesday, ended flat as a drop in oil prices weighed on energy and material stocks.
* Oil prices were down yet again on Thursday, with U.S. crude tumbling nearly 3 percent.
* Shares of Twitter were down 8.2 percent at $13.75 premarket after the company reported its first quarter with no increase in users since it went public.
* Cisco was up 3.7 percent at $23.35 after reporting a bigger-than-expected quarterly profit.
* Tesla said it expects to become profitable in 2016. The stock, which rose more than 10 percent after-hours on Wednesday, was up 2.2 percent at $147.30 premarket on Thursday.
* Expedia soared 10.2 percent to $104 after it forecast higher 2016 profit. Peer TripAdvisor was also up 10.4 percent at $60 after its profit beat estimates.
Futures snapshot at 7:10 a.m. ET:
* Dow e-minis were down 313 points, or 1.97 percent, with 67,813 contracts changing hands.
* S&P 500 e-minis were down 37.25 points, or 2.02 percent, with 434,335 contracts traded.
* Nasdaq 100 e-minis were down 90 points, or 2.27 percent, on volume of 62,707 contracts. (Reporting by Aastha Agnihotri and Abhiram Nandakumar in Bengaluru; Editing by Savio D'Souza)