The sell-off in US stocks may have at least one day more to go if history is a guide, according to Fundstrat Global Advisors LLC.

The S&P 500 has fallen 4.3 per cent over the last two sessions, though remains up 53 per cent from its March lows at the height of fears about the coronavirus.

The tech-heavy Nasdaq 100 Index fell 6.4 per cent over Thursday and Friday. Given those substantive declines and the three-day Labor Day weekend, technical strategist Robert Sluymer says there’s a risk of a further downdraft.

“We would not be surprised to see the three-day rule take effect,” Sluymer wrote in a note. Steep sell-offs often take at least three days to wash out the panic sellers.

Nasdaq 100 futures fell as much as 2.1 per cent in early Asian trading Monday.

The sudden back-to-back losses came after a ferocious run-up notable for a rare simultaneous increase in volatility, the outperformance of a few megacaps and unusually heavy options volume. Some strategists see it as simply a removal of froth, rather than a longer-term decline, while Fundstrat’s view remains unchanged that the recent drop is a ‘healthy consolidation’, Sluymer said.

The Nasdaq in particular tends to fall very rapidly from its peaks, according to Jason Goepfert, the founder of Sundial Capital Research Inc. “So if it is really a top, there could be an almost straight-down move in the weeks ahead,” he warned in a note Friday.