FRANKFURT (Reuters) - Deutsche Boerse (>> Deutsche Boerse AG) has won further backing among its shareholders for its planned merger with the London Stock Exchange Group (>> London Stock Exchange Group Plc), with the German exchange operator reporting a 55.5 percent approval rate on Wednesday.

Deutsche Boerse had asked its shareholders to back the $27 billion (20.5 billion pounds) merger and last week lowered the acceptance threshold to 60 percent from an earlier 75 percent of its shareholders.

The acceptance period for the third attempt by the LSE to merge with Deutsche Boerse in around 16 years has been extended until July 26.

Deutsche Boerse Chief Financial Officer Gregor Pottmeyer said in a statement he was "very confident" of reaching the threshold approval.

"It is common market practice for investors to tender only in the final 48 hours before the expiry of a tender offer," Pottmeyer added.

Last Wednesday, shareholders' approval crossed the 50 percent barrier, meaning that many index funds are now able to tender their shares, as their internal guidelines often demand they act only once that threshold has been reached.

(Reporting by Tina Bellon and Andreas Kroener; editing by Adrian Croft)

Stocks treated in this article : Deutsche Boerse AG, London Stock Exchange Group Plc