BGCP is the poster boy for manipulation: Monday, on heavy volume, the stock gets attacked and closes at $3.85; weak hands sold and lost a 40% runup today on a buyout! Yesterday's sellers must be in a state of shock.
Best thing to do is to hold some dry powder in reserve at all times for this one. Pick it up on the walk-down and ride it up again. When the real up trend starts, it'll probably be pretty dramatic but there's pretty good money to be made on the swing in the meantime.