Macquarie Group will seek to sell $600 million in new capital through an issue of six million convertible preference securities at $100.Less than a week ago, in releasing its full-year profit to March 2008, the group said it had $3 billion in excess capital, but no doubt in the current climate Macquarie has plenty of ideas on how to put those funds to work.The Financial Review reports that Macquarie may seek to raise as much as $1 billion in capital through the preference share sale.There appears to be a strong retail bias to the plans to sell the preference shares, with six broker groups, including nabCapital and Westpac hired to help sell the shares.Standard & Poor's assigned a BBB credit rating to the CPS, with Moodys a rating of Baa1.It isn't clear what margin Macquarie expects to pay. The interest rate on the Macquarie preference shares will be fixed rate, unlike the floating rate on some recent issues.Suncorp, with a slightly better credit rating of A-, two weeks ago sold $700 million in preference shares at 320 basis points over the swap rate.The group will conduct a bookbuild with institutional investors to set pricing on June 3. The shareholder priority offer for the Macquarie share sale opens June 5.The preference shares are convertible after five years.