United Guaranty last week filed papers for an initial public offering with the Securities and Exchange Commission as a first step to split from its parent company, American International Group, Inc. UG, the mortgage insurance subsidiary of AIG, has filed a proposed aggregate offering of $100 million of common stock but pricing has not been determined. The IPO will not launch until later this year, but if the weak IPO market picks up soon, “it would change things a great deal,” according to an analysis by investment research firm Seeking Alpha. In late January, AIG announced...