UPDATE 2-Equifax profit falls as hacking costs take toll

(Adds details on financial results, quote from regulatory filing, background on hack)

Nov 9 (Reuters) - Equifax Inc on Thursday reported lower quarterly profit, and quarterly revenue missed estimates, as the credit bureau warned that its massive data breach had prompted some customers to hold back business.

The hack, which compromised sensitive data of some 145.5 million people, has harmed the company's reputation and prompted investigations in every U.S. state, a federal criminal probe and scores of lawsuits. Equifax said it was not possible to estimate how much it would cost the company to respond to those probes and investigations. The Atlanta-based company said it recorded $87.5 million in expenses related to the hack during the quarter, including legal fees, investigation of the breach, and credit monitoring for U.S. consumers whose data was exposed in the breach.

Equifax estimated a range of additional costs between $56 million and $110 million to continue providing the free services.

The company warned there could be further attacks. We cannot assure that all potential causes of the incident have been identified and remediated and will not occur again, it said in a quarterly filing with the Securities and Exchange Commission.

Eric Johnson, dean of Vanderbilt Universitys Owen Graduate School of Management, said that uncertainty could cost Equifax future business.

They need to be able to nail those pieces and have a clear explanation of what happened and how they solved it, said Johnson. I think they can get there, but they arent there now.

Johnson estimated the costs from the breach will total in the hundreds of millions of dollars, but that lost revenue could be even larger.

The company said the breach was already taking a toll on sales.

"We believe that certain of our customers have determined to defer new contracts or projects unless and until we can provide assurances regarding our ability to prevent unauthorized access to our systems and the data we maintain," it said in a regulatory filing.

The company reported third-quarter revenue of $834.8 million, missing analysts' average estimate of $845.94 million, according to I/B/E/S Thomson Reuters.

Adjusted for one-time costs, such as hacking- and merger-related expenses, Equifax said it earned $1.53 per share, beating an average of analysts' estimates by 4 cents, according to Thomson Reuters I/B/E/S.

Net income attributable to Equifax fell to $96.3 million, or 79 cents per diluted share, from $132.8 million, or $1.09 per diluted share, a year earlier. (Reporting by John McCrank in New York; Editing by James Dalgleish and Jim Finkle)