 Shares of Obalon Therapeutics Inc. blasted five-fold higher on massive volume in midday trading Wednesday, after the weight loss technologies company announced an agreement to merge with weight loss solutions company ReShape Lifesciences Inc. . Obalons stock rose 401.6 toward the highest close since July 2019, while trading volume soared to 250.3 million shares, compared with the full-day average of about 626,000 shares. 