Varonis rises after Proofpoint agrees to $6.3 bln takeover
** Shares of Varonis Systems VRNS.O rise 2.4% to $48.50 premarket
** Private equity Thoma Bravo-owned Proofpoint said to buy the data security firm in $6.3 bln all-cash deal
** Offer values VRNS at $49.75/share — 52% premium over close on June 22, the day before speculation about possible sale emerged
** Deal expected to close in H127
** Nine of 22 brokerages rate stock "buy" or higher, 13 "hold"; median PT: $50
** As of last close, stock up 44.3% YTD