When will it happen? The biggest question in investors’ minds — aside from the future of Greece and the euro — did not get resolved on Wednesday. But judging from the modest rally by the key indexes, the market appears ready for the first hike in U.S. short-term interest rates to occur sometime this year. It was a lightly seesawing session, but both the Nasdaq composite and the S&P 500 ended up mildly in the black, up 0.2%.