Bitcoin broke the $20,000 barrier and was about to have its best day in six weeks on Friday. Market participants said there was no particular trigger for gains beyond a broad optimistic mood across asset classes, led by a fall in the safe haven dollar and a rally in Chinese equities.

Bitcoin, the largest cryptocurrency in terms of market value, rose more than 7% to $20,796, a two-week high. Ether, the second largest, rose 5% to also reach a two-week peak at $1,717. Bitcoin had been as low as $18,540 on Wednesday.

If cryptocurrencies can keep their gains through Sunday's close, bitcoin could register a second consecutive weekly rise, and its best week in about a month. Ether's volatility over the weekend could be exacerbated by an impending software update known as a “merger,” scheduled between September 10 and 20, with the exact date uncertain.