Bitcoin drops 5% to its lowest level in 3 months as risk assets continue to get crushed

Bitcoin fell to its lowest level in three months on Monday as investors dumped risk assets amid expectations of higher interest rates.

The world's largest cryptocurrency dropped as much as about 5% to an intraday low of $18,276, reaching its lowest level since June 19. It was last down 2.9% at $19,166.00. Bitcoin is down 7.2% this month and on pace for the second straight negative month after plunging 15% in August.

Ether also fell a similar 5% to $1,281 apiece Monday, hitting its lowest level since July 15. It was last lower by 1.9% at $1,354.86. It's currently down 17% this month, on track to post its worst month since June.

Risk assets have been under massive pressure as the Federal Reserve is expected to stick to its aggressive tightening schedule. The central bank is widely expected to approve this week a third consecutive 0.75 percentage point interest rate increase that would take benchmark rates up to a range of 3%-3.25%. 

"Retail buyers have a long term outlook on bitcoin while institutional traders are treating digital assets like tech stocks and adopting a short term mentality that's contributing to the selloff we're seeing," said Chris Kline, chief revenue officer and co-founder of Bitcoin IRA. "The tightening policy at the Fed is strengthening the dollar and is weighing down risk assets, overall."

— CNBC's Gina Francolla contributed to this report.