U.S. Federal Reserve Chair Janet L. Yellen, Washington, Feb. 10, 2016
U.S. Federal Reserve Chair Janet L. Yellen testifies before the House of Representatives Financial Services Committee on Capitol Hill in Washington Feb. 10, 2016. Nicholas Kamm/AFP/Getty Images

Come Tuesday, investors will be reading the silence ahead of next week’s U.S. Federal Reserve policy committee meeting, with the last word coming Monday afternoon from Fed Governor Lael Brainard, who is scheduled to speak at the Chicago Council on Global Affairs.

Also making appearances earlier Monday are Atlanta Fed President Dennis Lockhart before the NABE conference in Atlanta and Minneapolis Fed President Neel Kashkari at a question-and-answer session in St. Paul, Minn.

Investors sent stocks down nearly 400 points Friday amid indications from two other Fed governors last week that the central bank could raise interest rates at the Sept. 20-21 meeting — something investors had thought was off the table until December.

Brainard is seen as the most dovish member of the Fed board, and Peter Boockvar told CNBC any hawkish comments from her would pretty much guarantee a hike.

“For a stock market that is wholly unprepared for that, not only could it get messy, it will get messy,” he said. “The only reason why we're at these [stock market] levels is because of low interest rates and central bank policy. ... When the Fed removes accommodation, things are seen for what they really are, not for what people want them to be.”

Federal Funds Rate - 1 Year | Credio

The CME Group fed funds futures indicated there is a 27 percent likelihood of a September rate hike and a 46 percent chance of one in December, TheStreet reported.

A final decision likely will rest on retail sales and producer price data, the Philadelphia Fed Business Outlook Survey, the Empire State Manufacturing Survey and industrial production data out on Thursday, and consumer price data Friday. Friday also constitutes a quadruple witching session.

Jobs data, car sales and data from the services and manufacturing sectors all have undershot forecasts so far this month, Reuters noted.

“It would take a big increase in retail sales, increase in inflation to get the Fed to even think twice [about September],” said Paul Christopher, head global market strategist at Wells Fargo Investment Institute in St. Louis.

Speculation about an interest rate hike also is being fueled by the European Central Bank’s decision not to extend its asset-buying program beyond March.

“Expectations that the Fed could raise interest rates this month are on the upswing again following Thursday’s ECB meeting where it apparently didn’t discuss new stimulus — a shift from dovish to neutral that has opened the door for the Fed to raise interest rates soon,” Colin Cieszynski, chief market strategist at CMC Markets, told MarketWatch.