Mitsui Sumitomo Insurance Group Holdings Inc., Aioi Insurance Co. and Nissay Dowa General Insurance Co. are in talks to create Japan's largest nonlife insurer, two sources said Monday.

The three companies, with a combined market value of about ¥1.78 trillion, may merge as early as the second half of 2009, one of the sources said.

Both declined to be identified because a final decision hasn't been made.