TOKYO, Jan 8 (Reuters) - Bitcoin fell more than 5% on Friday, a day after topping $40,000 for the first time.

The world's most popular digital currency fell as low as $36,750 on Bitstamp exchange, after reaching an all-time high of $40,402.46 in the previous session.

Rival cryptocurrency Ethereum sank more than 10% to as low as $1,087. (Reporting by Kevin Buckland; Editing by Tom Hogue)