The independent refiner announced a secondary offering of 7.8 mil shares from Delek Hungary Holdings. Delek US' board also authorized a $75 mil stock repurchase program. Delek US (DK) halted trading before the news broke midday. Last week the company reported revenue above analyst estimates. U.S. oil refiners have been surging in recent months as the influx of cheap natgas has prompted oil and gas giants to shift to fracking operations for shale oil. Delek's shares fell 1.3% to 39.98, although its stock has risen 60% on the year, closing Mon. to a new high of 40.50.