Goldman Sachs Group Inc plans to start disclosing more financial information to investors, including how much of its revenue comes from trading and investing its own money, a person familiar with the matter said.

The change comes after years of complaints from investors, analysts and others that the bank does not disclose enough information about exactly how it makes money.

Goldman has prepared a 63-page report after a more than eight-month internal review, the person said. The results of the review are set to be released publicly on Tuesday, he added.

Many investors have complained that Goldman Sachs is a black box and that forecasting how its earnings will change over time is extremely difficult.

Goldman declined to comment.

The bank's willingness to change is the latest sign of how financial reform and investor pressure are spurring banks to change the way they do business. Morgan Stanley said earlier on Monday it was planning to spin off a unit that trades the firm's own money.

The bank's chief executive, Lloyd Blankfein, reported the results of the report to about 470 of Goldman's senior employees on Monday, the source said.

Goldman Sachs plans to release fourth quarter 2010 results on January 19. Those results will include the extra detail that the bank plans to start reporting regularly.

The story was originally reported by the Wall Street Journal.

(Reporting by Dan Wilchins; editing by Bernard Orr and Andre Grenon)