** U.S.-listed shares of major Chinese retailers fall premarket after Trump signs an executive order that closes a trade loophole known as "de minimis"

** "de minimis" allowed packages valued at less than $800 from China and Hong Kong to enter the U.S. duty-free and with minimal inspections

** Alibaba Group BABA.N fall 3%, while JD.com JD.O and PDD PDD.O down 4.7%

** Imported goods sent through the postal network and valued at or under $800 would now be subject to a duty rate of either 30% of their value or $25 per item, with that rate increasing to $50 per item after June 1

** On February 1, Trump ordered an end to duty-free entry for cheap Chinese goods but later paused it due to disruptions for customs, delivery services, and online retailers

** PDD Holdings' co-CEO Chen Lei last month told analysts to expect "challenges" for its global business, adding that PDD's response includes exploring new business models and experimenting with "innovative localised supply chain solutions"

(Reporting by Kritika Lamba in Bengaluru)

((Kritika.Lamba@thomsonreuters.com))