US STOCKS-Futures edge up a day before Brexit vote
* Futures up: Dow 22 pts, S&P 2.25 pts, Nasdaq 8.25 pts
By Tanya Agrawal
June 22 (Reuters) - U.S. stock index futures were slightly higher on Wednesday as investors held off from making big bets, a day ahead of Britain's referendum on its European Union membership.
* Traders are guardedly optimistic about a "Remain" vote. While polls are extremely close, bookmakers have pointed to betting patterns in favor of the U.K. remaining in the EU.
* Investors will also keep an eye on U.S. Federal Reserve Chair Janet Yellen's second day of testimony to Congress on the health of the economy.
* On Tuesday, Yellen was optimistic about the economy and played down the risk of a recession, but warned that the British vote on Thursday and a U.S. hiring slowdown posed risks to the economic outlook.
* Yellen's comments pointed to a cautious central bank, virtually ruling out a July rate hike. The Fed also warned U.S. stock market valuations are "well above" their median over the past 30 years, the strongest such assessment in years.
* The S&P 500 is trading at about 16.5 times expected earnings, above the 30-year median of 14.6 times, according to Thomson Reuters Datastream.
* Data on Wednesday includes U.S. home resales at 10 a.m. ET (1400 GMT). A Reuters survey of economists forecast a 1.1 percent rise in existing home sales to an annual rate of 5.54 million units last month, following a 1.7 percent gain in April. Continuación...