Billionaire Leon Cooperman advised investors on Wednesday to stay away from bonds as they are in a bubble.

"My world is cash and stocks. I think bonds are the bubble, not stocks," Cooperman told CNBC's "Halftime Report." He also noted investors should buy stocks they see as "fundamentally cheap" after a recent decline in equities.

Cooperman's comments come after the benchmark 10-year note yield rose to 3.261 percent last week, its highest level since 2011. The sharp rise in rates spooked investors across the globe, with world equities falling sharply last week.

The Federal Reserve dropped its overnight interest rates to zero in the aftermath of the financial crisis as it tried to jump-start the U.S. economy. This pushed yields down to historical lows, thus sending bond prices higher and to levels that some investors like Cooperman say reached bubble proportions. Now the Fed is reversing these policies by rising interest rates and trimming its balance sheet. The central bank has already hiked rates three times this year and is forecast to raise them once more before year-end.