Baker Hughes /zigman2/quotes/205323712/composite BKR -0.13% on Friday reported that the number of active U.S. rigs drilling for oil edged down by 4 to 181 this week. That followed a decline of 3 oil rigs a week earlier. The number of oil rigs has not seen an increase since the week ended March 13. The total active U.S. rig count, meanwhile, fell by 5 to 258, according to Baker Hughes. August West Texas Intermediate crude held onto their gains following the data, trading up 56 cents, or 1.4%, at $40.18 a barrel on the New York Mercantile Exchange.