 "Wall St Week Ahead: Investors look for signs in the rally's break")
Next week could make it harder to figure out, considering that the long Memorial Day weekend typically signals the start of the summer.
The three major US stock indexes posted a decline for the week on Friday, their first weekly loss since mid-April, raising some fresh worries that this year's rally may be weakening.
Among the biggest concerns for investors right now is how soon the Federal Reserve may be ending its stimulus program. The minutes released this week from the Federal Reserve's latest meeting showed some officials were open to tapering large-scale asset purchases as early as at the June meeting.
Volume picked up sharply in the last two days following Wednesday's release of the Fed's minutes.
"We should have already been prepared for" the Fed's eventual tapering of stimulus measures, said Bryant Evans, investment adviser and portfolio manager at Cozad Asset Management, in Champaign, Illinois.
"The market is perhaps just looking for an excuse to sell off some gains. And then you throw in the 'sell in May and go away' philosophy, well, here we are Memorial Day weekend."
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The pickup in volume suggested to some a shift in sentiment, though activity has been below-average throughout the rally, which has taken the Dow and the S&P 500 to record highs.
Much of that rally has been driven by the Fed's continued economic stimulus.
Short pullbacks
The duration and the scope of the rally have surprised even veteran market watchers, many of whom have been expecting a reversal in the trend for several weeks.
The market has managed to avoid any significant pullback since November, and dips have been used as buying opportunities. Even with the week's 1.1% loss, the S&P 500 remains up 15.7% for the year.
Volatility has also not been a problem.
That's why Wednesday's reversal - where the Dow and the S&P 500 both rose more than 1% during the morning, but fell more than 1% in the afternoon - caused many investors to take notice.
"That's a change. Historically, when you get that kind of a reversal day, it kind of stalls things out for a while," said Frank Gretz, market analyst and technician for brokerage Shields & Co in New York.
But he said the market's up trend has mostly been orderly, with little divergent action.
Other analysts see some of the market's strong momentum finally waning. This week's decline caused the S&P 500 to trade below its 14-day moving average, but the index managed to close above the level.
In another possible sign of weakening sentiment: Two massive blocks of puts were bought on Friday on the iShares MSCI Emerging Markets Fund and the Vanguard FTSE Emerging Markets Fund , according to options strategists.
The move suggests investors are hedging against a possible decline in emerging markets in the weeks and months ahead.
"Buyers can only take stocks so far. There's certainly a little bit of buyers' fatigue setting in, and with the market being as extended as it is, it's certainly not unrealistic to think sellers will start to come in and take advantage of the strength we've had," said Michael James, managing director of equity trading at Wedbush Securities in Los Angeles.
That's not to say the up trend is over, he said.
Bond yields and equity gains
Some of the recent rally has reflected a push out of bonds and into stocks.
Equity valuations tend to be lower when real 10-year US Treasury note yields are above 4% or below 2%, Goldman Sachs analysts wrote in a recent research note.
"We expect both real and nominal bond yields to gradually rise from current low levels," the analysts wrote.
The benchmark 10-year US Treasury note's yield rose on Friday above the key 2% level - the highest in two months. Treasury yields rose this week after the Fed added to bond investors' fears that the US central bank might slow its bond purchases later this year if the economy improves further.
Investors are trying to determine if yields are likely to climb on stronger growth and a more hawkish stance by the Fed.
Economic data has remained mixed, adding further uncertainty to market projections.
Next week brings May consumer confidence data on Tuesday and preliminary data for first-quarter gross domestic product on Thursday. On Friday, personal income and consumption data for April is set for release, along with the final reading on consumer sentiment for May from Thomson Reuters/University of Michigan, and the ISM-Chicago business survey, also known as the Chicago Purchasing Managers Index, for May.