Some financial commentators say that with the S&P 500 and Dow Jones Industrial Average within 2 percent of record highs, stocks have entered bubble territory.

CNBC contributor Ron Insana disagrees.

Editor’s Note: Retire 10 Years Earlier With These 4 Stocks

"There is some concern that the stock market is nearing the type of peak last witnessed in 2007 and 2000, and that we're due for a historic pullback, or many years of subpar returns," he writes on CNBC.com. "I think that this time is different and that the environment today is not remotely the same as it was during those market peaks."

Some point to market valuations in arguing that stocks are overdone.

"It is true that stock-market valuations are stretched, with the price-earnings ratio on the S&P 500 at roughly 18 times earnings," Insana writes. "Prior peaks have been anywhere from 18-25X earnings before the market suffered an important setback."

But at prior peaks, lofty valuations were accompanied by rising inflation that prompted multiple interest-rate hikes by the Federal Reserve, he says. "And while it's true that the Fed is tapering its stimulus program, it is far from tightening monetary policy in such a way that would hurt stocks."

To be sure, stocks declined Friday.

"Russian troops are massing up at the Ukrainian border, which is enough to make people nervous about anybody with business activities in Europe," Tom Stringfellow, chief investment officer of Frost Investment Advisors, told Bloomberg News. "The great earnings surprises from some of the big tech stocks haven’t quite been enough to bring down the wall of worry."

Editor’s Note: Retire 10 Years Earlier With These 4 Stocks

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