What happened around 3-5-09 that made most big volume stocks to start increasing?

well, that's a really interesting question to which I have no answer. in terms of who profited, I would say that everyone who had most any investments (stocks. mutual funds, etc) stopped losing, the Dow is up nearly 4,ooo since then.

look at the leading indicators released b4 that eg. buffaloes nearly extinct etc.

If you look at almost any stock chart, it suddenly began increasing on (or very close to) 3-5-09 as if someone flipped a switch and shouted "OK, the stocks are low enough. It is time to begin increasing!" I must have been sleeping when that announcement was made.... Unfortunately for me.