A surprisingly strong US jobs report for November powered US stocks to another record performance, with the S&P 500 registering its seventh straight weekly gain.
Wall Street shares continued to take the good news as good for all -- more jobs, cheaper oil, stronger growth -- even as it raised the chance of earlier and sharper interest rate rises next year.
And, on the 18th anniversary Friday of then-Federal Reserve chairman Alan Greenspan's ominous warning of "irrational exuberance" in markets, the Street chose to ignore questions of rising risk-taking.
Instead, the week saw the S&P add 0.4 percent to a new closing record of 2,075.37, and the Dow Jones Industrial Average picked up 0.7 percent to a fresh mark of 17,958.79.
That gain took place even as Thanksgiving weekend sales in stores and online were solid but not stunning; despite the weakening of oil sector shares by the fall in crude prices; and even though major economies in the rest of the world, particularly the eurozone and Japan, remained disturbingly weak.
For many the US economy continued to justify buying in.
Friday's gains came on the back of the best monthly jobs report in more than two years. The US economy churned out 321,000 net new jobs in November, 90,000 more than economists expected. The gains were strong through a broad range of industries.
Coupled with the plunge in gasoline prices, it means US consumers are enjoying much better gains in their wallets.
"The US market continues to be the best market compared to China, Japan and Europe," said Michael James of Wedbush Securities.
"Overall, with the better numbers for both earnings and economic data, the momentum continues higher in the US market. I dont expect it to abate by the end of next year."
- 'Excessive risk-taking' -
But some analysts were worried about the recent runup. In its seven-week winning streak, the S&P 500 has added 10 percent. And even as oil prices continued their fall this week, share prices of oil industry firms recovered, as investors plunged back in, in the belief that they were oversold.
On Tuesday the US Treasury's Office of Financial Research (OFR) warned that the cheap money the Fed and other major central banks have been pouring into the financial system could be artificially inflating assets and driving more risky behavior in the financial sector.
"We see material evidence of excessive risk-taking during the extended period of low interest rates and low volatility," the OFR said in a report to Congress.
"We are concerned that financial activity is migrating toward areas of the financial system where threats are more difficult to assess because information is not available, and that activity may be consequential."
The OFR pointed to the momentary, still-unexplained flash crash in the US Treasury bond market on one day in October as a sign of what could happen in markets increasingly dominated by hyper-speed computerized trading decisions.
"We believe there is a risk of a repeat occurrence, given the increased prevalence of algorithmic trading, a shift in risk preferences by broker-dealers, and the persistent incentives for risk-taking."
The Treasury warned that no one is certain how the Fed's expected move next year to tighten monetary policy after six years of zero interest rates will affect the markets.
For Mace Blicksilver of Marblehead Asset Management, the issue is just how much of the market's gains are driven by the Fed's cheap money policies.
"The question is, when this stimulus is removed, will this deflate like a pancake? We don't really know how it's going to turn out," he said.
It was 18 years ago on Friday when Greenspan made his most famous statement, in the form of a fraught rhetorical question.
"How do we know when irrational exuberance has unduly escalated asset values?"
The question came after the Dow had run up 70 percent in two years, and Greenspan's oracular musing sent a shudder through markets.
But that lasted for all of about a week.
The Dow then continued its upward march, adding 83 percent from when he spoke until the beginning of 2000, when the exuberance finally ran out.