Richard Thaler Chatham House/Flickr The winner of this year's Nobel Prize in economics says he's "nervous" about stocks.

"We seem to be living in the riskiest moment of our lives, and yet the stock market seems to be napping," Richard Thaler, who won the prize for his contributions to behavioral economics, told Bloomberg TV on Tuesday. "I admit to not understanding it."

"I don’t know about you, but I’m nervous, and it seems like when investors are nervous, they’re prone to being spooked," he said, adding that "nothing seems to spook the market."

Stocks have been on an upward trajectory for years, and back in September the S&P 500's bull run became the second-best-performing since World War II. The benchmark index has climbed about 270% from its March 2009 low.

They have continually touched new highs since President Donald Trump's election in November 2016, attributed to strong corporate-earnings growth and Wall Street's hopes of business-friendly policies.

Thaler was awarded the 2017 Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel on Monday.

Check out the full story at Bloomberg here.