TOKYO :Credit ratings agency Fitch on Thursday placed five Taiwanese life insurers under review for potential downgrades after a sharp surge in the Taiwanese dollar this month put stress on their balance sheets. Fitch put Cathay Life Insurance, Fubon Life Insurance, KGI Life Insurance, Nan Shan Life Insurance and Taiwan Life Insurance on "Rating Watch Negative" due to the "substantial currency mismatch" produced by their "sizeable" U.S. dollar holdings, the ratings agency said in a press