The S&P 500’s energy sector was suffering a unanimous selloff, as crude oil CL00, -6.54% and natural gas futures NG00, -2.41% slumped amid growing demand concerns and as the Biden administration calls for a gas-tax holiday. The SPDR Energy Select Sector ETF XLE, -4.51% dropped 3.4% with all 21 equity components losing ground, as crude oil futures shed 4.4% and natural gas futures lost 1.0%. Futures ES00, -1.37% for the S&P 500 SPX, -0.92% were down 1.4%. The energy ETF’s biggest decliners were shares of Marathon Oil Corp. MRO, -7.79%, down 5.2%, and Devon Energy Corp. DVN, -7.18%, down 4.5%. Among other more-active components, shares of Occidental Petroleum Corp. OXY, -5.03% slid 3.4%, Exxon Mobil Corp. XOM, -3.27% declined 3.0% and Kinder Morgan Inc. KMI, -3.00% shed 2.6%. The best performer was Williams Companies Inc.’s stock WMB, -3.18%, which fell 1.9%.