SAN FRANCISCO (MarketWatch) -- Credit reporting agencies Equifax Inc. EFX, -0.69% , Experian PLC EXPN, +2.37% , and TransUnion Corp. have said their credit reports have been breached by computer hackers, according to media reports Tuesday. The confirmation comes after reports from TMZ.com Monday that several celebrities ranging from Michelle Obama to Paris Hilton had their financial information posted online.