Just remember that as far as buybacks go, the company is limited in the % of daily volume they can purchase (not sure of the % amount, maybe 20%?). Also, they can only buy on the bid not the ask. So they can protect the bid support but not push the price by hitting the ask.
Also, no purchases during the first and last 30 min of trading.
That's what i've heard and I could be wrong.
B