The Federal Housing Finance Agency is toying with the idea of “grandfathering” the membership of captive insurance affiliates in the Federal Home Loan Bank system, while blocking out others, according to industry observers tracking the matter. Such a final rule would benefit MBS-investing real estate investment trusts that gained entry through a captive. A few years back, several REITs found a loophole in the FHLBank membership rules and exploited it before the FHFA put a moratorium on new captives joining the system. The moratorium expired...