A weak Monday morning open was a good setup for a mild oversold bounce. The dip-buyers had an opportunity to jump in early and they were able to hold on during the day. This, in turn, attracted a few more buyers who were worried the market might run up without them. Not too many folks were concerned as volume was very light, although breadth was solid.
The main driving force behind the market right now is the situation in Greece. The markets opened weakly because a deal to bail the beleaguered country out did not happen over the weekend. But the market gained its footing as the players seemed to adopt the stance that they just aren't going to allow Greece to go down. It will be bailed out at some point, but lots of posturing will take place first.
We could easily see some more upside in the near term -- especially if we hear any positive news out of Europe -- but there is no compelling reason at this point to believe that the market has made a near-term bottom.