Even though it's more history than not, first quarter GDP is the number traders will be watching Friday for what it might say about the current slowdown that began in March.
Economists expect first quarter GDP grew by 3 percent, a sharp increase over the fourth quarter's 0.4 percent rate, according to Reuters. But they expect the first quarter to be about double the slow growth expected in the current, second quarter.
(Read More: Global Slowdown Powers US Higher)
"It's hard to know what to make of it because the third quarter ended on a kind of sour note," said Chris Rupkey, chief financial economist at Bank of Tokyo-Mitsubishi. He noted that both durable goods and retail sales were soft in March, and capital spending was off.
"It does appear to be a one off," he said. Economists generally expect the current quarter to be the slowest growing of the year, and by the end of the year, the growth rate is expected to pick up to closer to first quarter levels.
Rupkey expects first quarter growth of 3 pecent, then a slowing to 1.5 percent in the second quarter; a pickup to 2.7 percent in the third quarter and then 2.9 or 3 percent in the fourth quarter.
Ward McCarthy, Jefferies chief financial economist expects 2.4 percent growth, for the first quarter. "I'm below consensus. The economy slowed down a lot late in the quarter," said McCarthy. "The question is how much of that is going to be captured in the data. I think the risk is on the high side." The number will be revised twice by the end of June, as new data comes in.
"The first cut of GDP has a certain roulette wheel aspect of it. The weakness in the latter part of the first quarter is carrying into the second quarter. Second quarter is likely to be softer than first quarter, but I am also convinced that as time goes on it will generate more momentum," he said. He expects growth of 1.5 percent for the second quarter, 2.4 percent for third quarter and 3 percent for fourth quarter.
"Housing keeps doing better. We have developments in the energy sector that are exciting. There are certain components – inventories, government spending and trade that can make a big difference in the measured growth rate, but don't really tell you what's going on in the economy," he said.
(Read More: Housing's Spring Bloom 'Stuck' Due to Short Supply)
But Rupkey said first quarter GDP could even come in higher than the 3 percent anticipated in markets. "I think the wild card is always that we can't figure out defense spending and inventories are also impossible to forecast. Those two things could easily add 0.7 to it if the stars were aligned," he said.
Stocks enter the final trading day of the week with strong gains after last week's losses. The S&P closed up 6 at 1585 Thursday, within easy reach of its all-time closing high of 1593. The gain for the week is nearly two percent. The Dow was up 24 at 14,700, and is on track for a 1 percent gain for the week. The Nasdaqwas up 2.6 percent for the week-to-date at 3289.
Traders said the market took a dip around 3 p.m. ET on competing headlines from Fed Chairman Ben Bernanke and the Bundesbank. Traders said the headlines came right about the same time the sell on close orders increased at the NYSE.
Bernanke's comments were prepared remarks for the Financial Stability Oversight Committee. He said vulnerabilities remain in the market and the wholesale funding markets remain susceptible to runs. The other headline catching attention were media reports that the Bundesbank had criticized government bond purchases in a document filed with the German Federal Constitutional Court.
Friday's GDP data is released at 8:30 a.m. ET, and consumer sentiment numbers are reported at 9:55 a.m. ET.