BlackRock ( BLK - Get Report) and Pimco submitted proposals to manage troubled mortgage- backed securities in the biggest portion of the Treasury's $700 billion financial-rescue plan, Bloomberg reports, citing people familiar with the matter. Pimco is a subsidiary of German insurer Allianz ( AZ). State Street ( STT - Get Report)and Bank of New York Mellon ( BK - Get Report) bid to handle record-keeping and custody services for the Treasury, Bloomberg reports. The deadline for proposals was Wednesday. Last week, the House of Representatives passed the Treasury proposal for the bailout program for the financial system. President Bush signed the legislation on Friday.