BOSTON, July 23 (Reuters) - Affiliated Managers Group Inc (AMG.N: Quote, Profile, Research), a holding company for money managers, on Wednesday cut its 2008 cash earnings forecast due to the stock market's drop.

Its new forecast is $6.40 to $7.00 per share, down from an April forecast of $6.70 to $7.40, Affiliated said in an earnings conference call.

Cash earnings per share, a measure used by analysts and preferred by the company, are made up of net income plus amortization and deferred taxes related to intangible assets, plus affiliate depreciation, according to Affiliated. (Reporting by Muralikumar Anantharaman; editing by John Wallace)