But for those investors hoping to buy stocks at reasonable prices, the view isn't so pretty, notes Wall Street Journal columnist Jonathan Clements.

"My hope: we get a 25 percent decline in share prices," he writes. "That would make the market more reasonably valued and provide a buffer against disappointment. I’d have greater confidence that my next stock-market purchase would collect a decent long-run return."

A 25 percent drop for the S&P 500 index from Monday's close at 2041.32 would put it at 1,531. The index hit a record 2,046.18 Thursday.

"There are three reasons to fear slower earnings growth over the next 10 years," Clements says. 

"First, the recent gains have been driven by rising profit margins. . . . Second, economic growth may disappoint. . . . Third, over the past 10 years, companies have bought back as much stock as they’ve issued."

One area of the market where investors appear particularly bullish is consumer discretionary stocks. The S&P 500 Consumer Discretionary index has returned 1.7 percent so far this month, compared to 1.2 percent for the S&P 500 overall.

"Consumer discretionary is a good way to play the health of the U.S. economy, especially when you look overseas," Margie Patel, a fund manager at Wells Fargo Asset Management, told the Financial Times. "A lot of the companies are U.S.-focused in their revenues."

Related Articles:

• Citigroup's Levkovich 'Nervous' But Still Bullish
• Marc Faber: Stocks Still Headed for Major Correction