UPDATE 2-US SEC plans mandatory XBRL beginning in 2009

(Adds reaction, details of proposal)

By Karey Wutkowski

WASHINGTON, May 14 (Reuters) - Some of the biggest U.S. companies will have to file their financial results next year with digital tags aimed at making it easier for investors to analyze the data, under a proposal put forward by the U.S. Securities and Exchange Commission on Wednesday.

About 500 of the largest public companies would begin filing their financial data in XBRL, or extensible business reporting language, in early 2009 as part of the SEC's proposed timetable.

Most of the remaining companies would have to comply within the following two years, the SEC said.

XBRL electronic tags are like bar codes and can be attached to each piece of financial data. The SEC has a voluntary pilot program in which more than 70 companies file their financial data in XBRL.

China, Japan, the Netherlands and some other countries already require the use of XBRL or are about to do so.

"Interactive data will let the sunshine in as never before," SEC Chairman Christopher Cox said at a meeting where he and the other two Republican commissioners voted for the proposal. The Senate has yet to approve two Democrats nominated to the five-member SEC.

Cox also noted the potential for investors and analysts to use XBRL tagging to compare financial figures for specific companies over time or across industries. Further, XBRL could give smaller companies more exposure because industry analysts will be able to do their jobs more efficiently, he said.