Low interest rates, steady demand for new deals and large refinancing volumes were propping up commercial mortgage-backed securities shops. [The sector is now seeing the benefit of the Federal Reserves move to continue its bond-buying program and is expected to see issuance of $70-75 billion this year.]...Deutsche Bank and NorthStar Realty Finance Corp. put on hold the sale of the Hancock Tower in Chicago after securing a major tenant. [A group that included San Antonio-based Lynd Co. and New York-based Mount Kellett Capital Management agreed to pay $145 million for the propertys office component, which includes a parking deck.]...Jamestown Properties pulled the sale of 999 Peach Street in Atlanta in favor of recapitalizing the Class A office.