Commonwealth Bank joins rush back into RMBS market MAKING hay when the sun shines, Commonwealth Bank has joined the rush to take advantage of the return to health of the residential mortgage-backed securities market. With the help of Citi and Macquarie, plus CBA's own markets bankers, the nation's largest lender yesterday began marketing a $750 million RMBS deal ahead of pricing this week, hot on the heels of Westpac's $2.1 billion deal last week.