ROBERT SHILLER: I'm Thinking Of Pulling Back From The Stock Market Somewhat

Bloomberg TVRobert Shiller

Nobel prize-winning economist Robert Shiller has warned about the high valuations in the stock market. But he always caveated that with the fact that he was very much invest in stocks himself.

However, his tone has changed today.

"I'm still in the market," said Shiller on CNBC this morning. "But I'm thinking of pulling back somewhat."

Shiller noted that the cyclically-adjusted price-earnings (CAPE) ratio was unusually high right now at 26.

"Historically, it hasn't been that high many time in history," he said. "1929, 2000, 2007..."

CAPE is calculated by taking the S&P 500 and dividing it by the average of ten years worth of earnings. If the ratio is above the long-term average of around 17x, the stock market is considered expensive.

"It's really hard to forecast the market," he said. "It might continue this boom. But on the other hand, it is looking really high."