Confidence in the buy now, pay later sector is evaporating as US operator Affirm halted a bond sale on Friday after an investor backed out, in a move blamed on growing levels of credit rate volatility.

Affirm stock plunged 15.5 per cent in response to the Bloomberg report, and is down 82 per cent since November. US-focused rivals and merger candidates Zip Co and Sezzle hit multi-year lows on the ASX on Monday and have cratered more than 80 per cent in 12 months.