NEW YORK CITY-Boston Properties said late Friday afternoon ithad closed on its acquisition of 510 Madison Ave. from MackloweProperties, a $280.5-million deal first reported last month.Separately, SL Green Realty Corp. said in a statement that theclosing, and the retirement of debt SL Green held in conjunctionwith the boutique officer tower, was the main factor in raising itsfull-year earnings guidance from about $4 per share to $4.75.

At the start of 2010, SL Green had bought the first mortgageloan and senior mezzanine loan on 510 Madison, with athen-outstanding aggregate balance of $249.3 million, for $180.5million. The sale to BPX, which in 2008 paid $3.95 billion for theGeneral Motors Building and other Macklowe assets, meant SL Greenreceived full repayment of the loans. SL Green says it has realizedan unleveraged IRR of 55% on its investment.

“The repayment of our loans in connection with the sale of 510Madison marks the conclusion of one of SL Green’s most successfuldebt investments to date,” SL Green CEO Marc Holliday says in astatement. “It illustrates the overall success of our structuredfinance investment program as an activity that complements our corebusiness and has the potential to provide significant value to ourshareholders.” SL Green also cites better-than-expected leasingresults in revising its earnings guidance upward.