LN-ARB

Fresh from being bought out by Starwood, LNR was recently in the news regarding risk retention in the CMBS stack. Financial Times and Debtwire did a nice job of covering LNR's stance on retaining (or selling) the B-piece in a CMBS structure.
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For the uneducated, one of  the ways LNR became great in good times (and  weak, in bad times) was through buying the first-loss portion, also known as the B-piece, in CMBS deals. The B-piece buyers are also known as the "Gatekeepers" in the securitization because since they are first exposed to losses in the trust, they get to have a say as to what assets are included.  If a particular commercial-mortgage isn't up to snuff, then the B-piece buyer gets to "kick-out" the collateral in lieu of something of better quality.
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During the euphoria that was 2007, the B-piece buyers could be counted on to keep some kind of credit standard within a CMBS deal.  The shortened version of the role of the B-piece investor is that by purchasing the riskiest component of the CMBS, they get to choose what risks they are exposed to and earn a greater yield, at the expense of being the first to absorb losses.

Look at the chart below.  Typically, LNR will buy the lower half of the middle column which includes the BB tranche, B tranche and the non-rated portion also known as the B-piece.

The FT/Debtwire article goes on to say that with Dodd-Frank's securitization retention rules on the horizon, it is unclear as to how much of the B-piece LNR would have to retain and for how long.  Back in November the WSJ covered a similar issue regarding Rialto and BlackRock.  As this class of investors is known for having "skin in the game" by being long and strong the assets in the trust, they are shrewdly selling down some of their position (The BB & B tranches, for example) while they still can:

"On a notional basis that’s equivalent to about a 7% stake of a new deal. But recently, the BB portion (about 2% of the 7%) has been offloaded into a more liquid secondary market at roughly 8% yields, according to the buysider, a CMBS dealer and a trader.

Put another way, on a cash basis, given the discounted level B-piece buyers pay for their risky bonds, some buyers have retained only the equivalent of about 1% to 1.5% of CMBS deals after stripping away BBs. In doing so, they’ve recouped a major portion of their initial investment, the buysider said."

It's understandable that proponents of the CMBS market would want the league of extraordinary B-piece buyers to match their interests with that of the other investors in the securitization but as long as Dodd-Frank leave this loophole open, then others will keep on driving a truck through it.

*Here is the presale for GSMS 2013-GC10 by S&P, of which LNR bought the E(BB), F(B), G(NR) and R(NR) tranches.  
*Not for the faint of heart: The GSMS 2003-GC10 Prospectus*