After weeks of virtual dormancy, a bona fide stock-market selloff took hold on Wall Street.

On Friday, both the S&P 500 index SPX, -1.15% and the Dow Jones Industrial Average DJIA, -1.84% plunged below their 50-day moving averages, precipitated by a rout in equities and government bonds, like the 10-year Treasury note TMUBMUSD10Y, 0.668% , on intensifying fears that the Federal Reserve could finally pull the trigger on raising rates after a nearly 10-month hiatus.

Read: Jeff Gundlach’s Fed-tightening talk set stage for a stock, bond-market rout

Stocks have benefited from lower borrowing costs and have jolted lower because of the potential that the Fed’s easy-money punch bowl might be emptied.

Market technicians view so-called moving averages, like the 50-day and 200-day, as dividing lines between significant uptrends and downtrends in a security.

Check out:Dow logs nearly 400-point drop as rate-hike fear grips Wall Street

“Looks like the S&P 500 finally breaking down after slicing right through the 50-day moving average,” wrote technical analyst Mark Arbeter of Arbeter Investments on Friday as the stock slide was in full swing.

The S&P 500 slips below its 50-day moving average. FactSet

In an earlier note mentioned in MarketWatch column Need to Know, Arbeter wrote that a rotation by investors into the S&P 500’s various sectors has kept the market trading in a narrow range for the better part of a month a half. But that dynamic broke down on Friday as all 10 sectors of the S&P 500, led by a roughly 3% rout in rate-sensitive sectors like telecommunications and utilities, marched lower.

Friday’s steep selloff suggests that the market isn’t entirely prepared for a September rate increase when the Federal Reserve convenes for its two-day policy meeting Sept. 20-21.

And that could add to the slide and to volatility VIX, -0.46% in the coming days. On Friday, Wall Street’s Brexit jumped 40%, surging the most in a day since the U.K.’s vote to leave the European Union to 17.50.

On Monday, stocks were attempting to climb out of their hole as investors grappled with the prospect of higher interest-rate environment.

For Arbeter’s part, his research note suggested that he was planning on buying assets as they fell in value.