Traders Magazine By Phil Mackintosh, Chief Economist, Nasdaq We’ve talked before about how odd lots are increasing and often provide the best quote in stocks. It was the basis for our own proposals on intelligent ticks as well as some of the SEC’s new NMS II rules last year. It’s mostly the Securities Information Processors (SIPs) that discern between round and odd lots, only including round lot quotes into the public NBBO. Although, since December 2013, the SIPs have reported all odd lot . Exchange matching engines usually don’t treat odd lots any differently. Queue priority is unaffected, and odd lots will fill on a spread crossing order, even if that incoming order is a round lot, often giving those incoming orders price improvement.