Tower Group International’s shares fell again yesterday on concerns about the re/insurance company’s plans to take hundreds of millions of dollars in charges.Shares fell more than 50 cents, a 13 percent decline, to $3.81 yesterday, a 52-week trading low. The company’s stock has fallen 48 percent since Tuesday.Bermuda-based Tower said on Tuesday that it will add $365 million to its reserves to cover additional losses in its commercial insurance lines.Most of the additional losses occurred between 2009 and 2011. The company will also take a $215 million goodwill impairment charge.AM Best, Fitch Ratings and multiple analysts subsequently downgraded their ratings for the insurer.Tower postponed its second-quarter results in August, saying it needed to review its loss reserves.The $365 million charge covers several different commercial lines of business including workers’ compensation, multiperil insurance and auto insurance.The goodwill impairment charge stems from Tower’s commercial and specialty reinsurance businesses.The company said it is evaluating other intangible assets connected to the commercial and specialty and reinsurance segments and its personal insurance segment. It will take that charge in its second-quarter results.AM Best downgraded the company’s financial strength rating late Tuesday to “B++,” considered its “good” rating, from “A-,” its “excellent” rating.The agency said that the once well-regarded company may struggle to restore shareholder confidence after its reserve charges came in so much higher than anticipated.