Shares of Rite Aid Corp. RAD, +10.81% rocketed as much as 38.5% intraday before paring gains to be up 18.7% in very active afternoon trading Wednesday, after the New York Post reported that the drugstore chain rejected earlier this month a buyout bid that valued the company at more than $800 million. Trading volume swelled to about 16 million share, compared with the full-day average of about 4.3 million shares. On March 30, private-equity firm Spear Point Capital Management said it would pay $14.60 for each Rite Aid shares outstanding, the New York Post reported, citing Spear Point co-Founder Ron Bienvenu.