SAN FRANCISCO (MarketWatch) -- Oil futures for June delivery clm11 sank $9.44, or 8.6%, to settle at $99.80 a barrel on the New York Mercantile Exchange Thursday, deepening a slide sparked by a selloff in precious metals and weak jobs data. For a most-active contract, it was the first time since mid-March that oil closed below $100. Natural-gas futures for June delivery ngm11 fell 32 cents, or 6.9%, to $4.26 per million British thermal units.