UPDATE 1-Manulife takes Q3 loss on actuarial changes

* Q3 loss C$0.12 per share vs profit C$0.33 yr-ago

* Loss driven by changes to actuarial assumptions

* Stock gains offset by lower bond yields

TORONTO, Nov 5 (Reuters) - Manulife Financial Corp (MFC.TO) said on Thursday it had a loss in the third quarter as lower corporate bond yields and a change to actuarial assumptions offset stock market gains.

North America's largest life insurer said it had a net loss of C$172 million ($162 million), or 12 Canadian cents a share, in the third quarter ended Sept. 30, compared with earnings of C$510 million, or 33 Canadian cents a share, in the same period last year.

Stock market gains were offset by lower corporate bond rates and changes in the actuarial assumptions Manulife uses to value its assets and liabilities.

Toronto-based Manulife said the third quarter's adjusted earnings from operations was approximately C$803 million, based on a forward-looking estimate of normalized earnings the company released in August. That is in line with its estimate of normalized earnings between C$750 million and C$850 million per quarter for the remainder of 2009 and 2010.

"Underlying earnings and performance were solid this quarter, but our results were negatively impacted by lower corporate bond rates and strengthening of reserves for changes in actuarial assumptions," Chief Executive Donald Guloien said in a statement.

"We took actions to improve margins, increased our sales of products other than variable annuities, further improved our equity risk profile and continued to build toward fortress capital levels," he said.

($1=$1.06 Canadian) (Reporting by Andrea Hopkins)