There’s an old saying that when it rains, it pours. And unfortunately for investors everywhere, that rang true in the stock market on Friday.

It was ultimately a perfect storm of conditions. Even though US shares closed at a five-month high on Thursday, repeated signs of an economic slowdown in the prior weeks left them in a vulnerable position.

Then, as US investors slept, weak European manufacturing data sent the yield on 10-year German government bonds into negative territory for the first time in more than two years. European shares traded sharply lower in response.

An eerily similar scenario played out in the US not long thereafter. After a report showing manufacturing activity slumped to its lowest in two years, Treasurys tumbled, leading to a dreaded yield-curve inversion that hadn’t occurred since 2007.

That stoked already-simmering fears of a possible economic recession, and what followed was a weak and uncertain trading session.

All the while, as those forces played out on the surface, investors were showing their displeasure in another way for a solid week. According to data compiled by Bank of America Merrill Lynch, fund managers pulled loads of money of out stocks even before Friday’s sell-off.

It amounted to a vicious trifecta that handed US stocks their biggest drop in two months. And at a time when the market’s biggest tech stocks are under regulatory scrutiny and there are relatively few corporate earnings reports to move the dial, there doesn’t seem to be much relief on the horizon.