The downdraft came after the world’s largest digital currency more than doubled in 2019, with many participants struggling to pinpoint reasons for the rally.

Bitcoin slid as much as 14%, before trimming that loss to 5.5%, trading at US$7,253 as of 10.19am in London.

Ethereum, Bitcoin Cash and Litecoin were down about 5%-6%. The Bloomberg Galaxy Crypto Index tumbled 8.4%, heading for its largest one-day slide in a month.

Speculation over what underpinned the early-May surge in the anonymously owned tokens has run from a possible squeeze on short positions to investor relief that recent hackings and scandals weren’t disrupting the broader market.

Of particular note was conjecture that stronger buying of Bitcoin – the most stable digital asset – came from sellers of Tether, the once-stable intermediary coin on crypto platforms whose promoters recently said it was no longer backed by US dollars in a 1-to-1 ratio.

Last month the New York attorney general accused Tether and giant crypto exchange Bitfinex last month of participating in a cover-up to hide losses of about US$850 million.