Assured Guaranty story updated with response from Moody's in final paragraphs.NEW YORK ( TheStreet) -- Assured Guaranty ( AGO) shares were up 7% in late trading Tuesday after the company fought back against a downgrade from Moody's Investors Service ( MCO). The Moody's downgrade came late Thursday, after the market close. Assured Guaranty shares opened lower on Friday, though they quickly recovered, and were in positive territory before noon. The markets were closed Monday for the Martin Luther King Jr. holiday. Assured Guaranty fired back at 2:10 pm Friday with a press release that criticized Moody's and announced its board of directors had authorized $200 million in share buybacks. In addition to a point-by-point response to Moody's criticism of Assured Guaranty's financial strength, the bond insurer argued Moody's rating process "was conducted without the transparency mandated under the Dodd-Frank Act and required by Moody's own Professional Code of Conduct, which is posted on Moody's website. Specifically, Moody's still has not shared material capital model results with us, despite our repeated requests throughout the process. As importantly, on the limited information provided, Moody's would not discuss underlying assumptions used to achieve these summary results nor assure us that all Moody's rated companies are stressed similarly," the release stated. Further, Assured Guaranty announced it "intends to launch during 2013 a new municipal-only financial guaranty insurer to increase its penetration in the public finance market." The insurer will not carry a Moody's rating, the release stated. Friday's announcements, which received scant press coverage, did not appear to move the shares substantially. Nonetheless, they held onto midday gains to close at $15--about 2.7% higher than where they closed on Thursday. On Tuesday following the holiday they added to those gains, and were up 7.07% to $16.06 shortly before the close of trading Tuesday. Possibly helping matters along for Assured Guaranty were a pair of positive research notes that defended the bond insurer. "Now that the Moody's overhang is behind it, the company can finally begin to "operate" again without trying to appease a rating agency. In our opinion, Moody's methodology and actions make it clear that it no longer wants to rate the financial guaranty industry," wrote MKM Partners analyst Harry Fong on Tuesday. Fong retained his "buy" rating and $28 price target.