Активный Инвестор, да, они так и разъясняют
www.sec.gov/investor/pubs/regsho.htm
Selling stock short without having located stock for delivery at settlement. This activity would violate Regulation SHO, except for short sales by market makers engaged in bona fide market making activities. Market makers engaged in bona fide market making activities do not have to locate stock before selling short, because they need to be able to provide liquidity. Market makers are not excepted, however, from Regulation SHO’s close-out and pre-borrow requirements.