Jeremy Siegel: Markets to Yellen, you made a mistake

Is Wall Street sending the Federal Reserve a message? Wharton School finance professor Jeremy Siegel strongly believes so.

In an interview on CNBC's "Halftime Report", Siegel said he views stocks re-testing August lows as a signal that Janet Yellen should have raised rates in September.

"The uncertainty of a hike is really what's bothering markets," he said. "Investors wanted the rate hike to be over with."

Barring any catastrophes, he now expects the Federal Reserve to raise rates in either October or December.

Siegel sees bright spots in the market once investors stop being scared of the Fed raising interest rates.

"Dividend paying and value stocks will be good performers in the next three to six months," Siegel noted.

Longtime market bull Siegel predicts the Dow Jones Industrial average will hit 20,000 next year.

"I definitely think we will see Dow 20,000 in 2016," he said.

—By CNBC Producer Bree Kelly. Follow her on Twitter @Bree_Kelly