More on HollyFrontier's (HFC) Q1 results: Earnings rose 38% as refinery margins improved and revenue declined at a slower-than-expected rate. Refinery gross margins were $23.32/bbl, up 34% vs. $17.46/bbl in the year-ago quarter. Production averaged ~407K bbl/day. But operating expenses were $265.1M ($6.68/bbl) vs. $241.6M ($5.51/bbl). Shares -2.3% premarket.