Nasdaq chairman warns about 'bubbly valuations' in markets

Borje Ekholm, the chairman of Nasdaq OMX, has warned about "bubbly valuations" in financial markets as a result of ultra-loose monetary policy from the world's largest central banks.

Ekholm, who is also the CEO of Investor AB, one of Sweden's largest investors, said it was time to start talking about normalizing interest rates and the cost of capital.

"What happens when you get too much cheap capital -- which we've had for quite some time -- is of course, there is a risk you could get bubbly valuations in the financial markets. And that is clearly a risk," Ekholm told CNBC on Thursday morning.

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U.S. stocks hit new record highs last week, with the Dow rising 18 percent so far this year, while the Nasdaq is up 19.5 percent year-to-date.

As head of Investor AB, Ekholm oversees stakes in a number of Europe's largest companies including engineering firm ABB, drug firm AstraZeneca and telecom gear-maker Ericsson. He said the company's strategy was to own companies with Nordic roots, but which still did a lot of their business in the U.S.

Ekholm also warned about China's slowing growth and said it was one of the major risks for the global economy and the Asian region.

(Read More: China seen overtaking US as global superpower)

"I think the elephant in the room is still what's going to happen in China, which will have big effects on the rest of the globe, and here the uncertainty is still there," Ekholm said.

He added, however, that he was still bullish on China over the long-term because of its rising wealth and growing middle class.

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