ag mortgage investment trust on thursday said it has made a nonbinding proposal to buy fellow realestate investment trust western asset mortgage capital for about 60 million in cash and stock in a bid to upend westerns deal to combine with terra property trust new yorkbased ag mortgages 988ashare proposal which includes 890 in stock and 98 cents in cash represents a roughly 18 premium to wednesdays closing price for western western based in pasadena calif last month agreed to an allstock merger with privately held terra ag mortgage said it believes its proposal represents a financially superior bid and that it is ready to engage in talks with western shares of western were recently up 47 at 875 in premarket trading while shares of ag mortgage which closed wednesday at 606 were down 84 at 555