In this clip from the (V)ALT, Brian King from LODAS explains what an alternative trading system is and how it is used in his firm.

LODAS Markets Cuts Trading Fees for NAV REITs, Executes BREIT Trade Just 4.5% below NAV
LODAS Markets, operator of the fourth-largest alternative trading system in the U.S., announced reduced fees to trade NAV REITs* on the LODAS Marketplace...