A Maryland-based technology company, Aether Systems, has shed its main lines of business and re-invented itself as a portfolio buyer of mortgage-backed securities – and management believes that its corporate structure will give it a leg up over other investors. “The transition to Aether’s MBS business is underway,” said David Reymann, CFO of the Baltimore-based firm, in a conference call with investors that focused on Aether’s strategic decision to sell its telecommunication business and