Shares of Matador Resources Co. /zigman2/quotes/204387276/composite MTDR -2.12% shot up 8.1% in midday trading, amid a broad rally in the oil and gas exploration sector, after MKM Partners analyst John Gerdes turned bullish, citing an attractive valuation. Gerdes raised his rating to buy, about two months after downgrading the stock to neutral, while keeping his price target at $30. Gerdes noted that after the stock underperformed it peer group in early March, it was now reflecting an approximately 36% equity value upside, which merited an upgrade to buy. The stock had dropped 17.3% from its more than two-year closing high of $26.69 through Tuesday, while the SPDR S&P Oil & Gas Exploration & Production ETF /zigman2/quotes/203527521/composite XOP -1.36% fell 13.0% over the same time. The ETF rallied 3.7% in midday trading, with 38 of 41 equity components gaining ground, as crude oil futures /zigman2/quotes/209723049/delayed CL00 +0.61% surged 4.8% amid concerns that a container ship that ran aground in the Suez Canal to block traffic would lead to supply disruptions. Meanwhile, the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.25% rose 0.6%.