A.) Prices spiked at the beginning of the trading session and then quickly fell. The reason was the contractionary reading of the ISM services number. This was enough to keep prices subdued from the remainder of the day.
B.) The late day sell-off had two causes. First, traders were worried about Bank of America's announcement that they would sell additional stock. There is concern that current shareholders will be diluted. But the second reason is more important: people are concerned about the jobs report tomorrow. If the number comes in low it could get very ugly tomorrow.