HONG KONG -- ESR Cayman is poised to become the world's third-largest listed real estate manager after agreeing to buy rival ARA Asset Management for $5.2 billion. Hong Kong-listed ESR will buy its Singapore-based peer by issuing $4.29 billion worth of new shares at 27 Hong Kong dollars ($3.47) apiece, a 2.5% discount compared to the close on Wednesday, plus $519 million in cash from its own funds, debt and a share placement, it said in a statement. The balance will be offered in notes convertible to shares. Shares in ESR ended the Thursday morning session 10% lower at HK$24.95.