Updated from 8:33 p.m. ET to include information on after-hours trading.

NEW YORK ( TheStreet) -- The slow meltup may finally giving way to a slow meltdown.

Thursday saw those raising the alarm about the potential hard landing in China got some data to back up the thesis, and while most market watchers have been expecting Europe to slip into recession, there's still bound to be a chilling effect when the economic reports begin to confirm this, as the Eurozone purchasing managers' index did.

When the closing bell sounded, the S&P 500 had surrendered 1400, falling three days in a row, and was on pace for its worst week of the year. Even Apple ( AAPL) showed some wear, falling back below $600.

So is this the start of the long-awaited pullback in U.S. stocks? Well, right now the negative catalysts seem to outweigh the positive ones. The bears can point to high oil prices heading higher, expectations for a lackluster first-quarter reporting season next month, and the likelihood that the mild winter has exaggerated the improvement in U.S. economic data, pulling forward growth typically seen in the spring.

The bulls have already gotten arguably a year's worth of appreciation in the S&P 500, up 10.8% so far in 2012, in less than three months, and the prospect of the Federal Reserve embarking on another round of quantitative easing has dimmed decidedly in the past few weeks.

What's more, if Wall Street needed a moment to point to where the bullishness went overboard, it may have gotten it on Wednesday with Goldman Sachs and its generational call on stocks.

Real Money contributor Doug Kass took Goldman to task on Thursday, asking out loud if the firm may have inadvertently called a near-term top in equities. He also punched some holes in the arguments the Goldman analysts presented in favor of stocks, and noted that there's some diversion of opinion even within the firm itself

Tellingly, bond yields have crept back down over the past few days with the 10-year Treasury settling at 2.28% on Thursday.

Using common sense as a barometer, that fact that Goldman's call comes after close to six months of steady gains should be enough to give investors pause. For example, the Dow Jones Industrial Average, itself up 6.8% year-to-date, has nearly doubled off its March 2009 closing lows during the financial crisis. That move puts the blue-chip index within 8% of its record closing high of 14165 in October 2007.

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