The stock market has maintained its smooth upward pace since the government shutdown ended in mid-October.

Perhaps too smooth.

The record-breaking run that continued Friday is unnerving some on Wall Street who worry that stock prices are getting ahead of themselves.

The market sailed to its third straight weekly gain with the Standard & Poor's 500 index notching a fresh high and the Dow Jones industrial average nearing a new peak.

The Dow climbed 61.07 points, or 0.4%, to 15,570.28. It rose a little more than 1% for the week, and is up almost 19% this year.

The S&P 500 rose 7.70 points, or 0.4%, to 1,759.77 and is up 23.4% this year. That's just a fraction behind its 23.5% advance in 2009 when the market rebounded from the 2008 global financial crisis.

Stocks have been fueled by the belief that the Federal Reserve will maintain its economic stimulus program into next year. The shutdown appears to have boosted the market by increasing the likelihood that the Fed will extend its easy-money policies.

But the climb in share prices has been accompanied by rising complacency among individual and professional investors. That's historically been a warning sign of trouble ahead.

"Everyone is reading from same script — that you can't lose buying the dips because the Fed is by your side. And it's clearly working," said Patrick J. O'Hare, chief market analyst at briefing.com.

"The problem is: No one expects it not to work," O'Hare said. "Eventually that leads to higher levels of speculation that can make the setback, whenever that setback happens, more painful than it otherwise would be."

Optimism is everywhere, even among small investors who have been skeptical of stocks throughout much of the 41/2 -year-old bull market.

In the latest weekly poll by the American Assn. of Individual Investors, 49.2% of people responding said they're bullish. That's up from 29% in late August. Bearish sentiment slid to 17.6% from 43%. That's the lowest since January 2012.

Professionals are even more enthusiastic. A survey last week by the financial newspaper Barron's found that 65% of money managers are bullish. A mere 8% admitted to being bearish.

Margin debt, which is the amount of money that investors have borrowed to buy stocks, topped $400 billion for the first time last month.

The euphoria is showing up in big-name stocks, especially technology darlings.

Shares of online retailer Amazon.com Inc. bolted more than 9% to a record high Friday after the company reported a 24% surge in third-quarter revenue but not a dime in profit — a $41-million loss instead.

Google Inc.'s stock bolted almost 14%, to top $1,000, after the online-search giant's third-quarter profit report last week.

Interest in initial public offerings is very high, especially the upcoming debut of short-message phenomenon Twitter Inc.

Shares of Potbelly Corp. more than doubled in its initial public offering three weeks ago.

"They make sandwiches," O'Hare said. "There's not a huge competitive moat there, and the stock doubled on its first day. There's a lot of money looking around for somewhere to go."