4:30 pm : Stiff selling on heavy volume came as the greenback spiked against foreign currencies and financials faltered. Stocks now head into Friday with a week-to-date loss of nearly 1%.

The dollar made its way to a 1.1% gain against competing currencies after Standard & Poor's downgraded Greece's debt rating. It was the second reduction of its kind this week. Support for the greenback had the Dollar Index up as much as 1.4%, which put it at a new three-month high.

That proved to be a headwind for both stocks and commodities, which put materials stocks under the most pressure this session. The materials sector settled with a loss of 2.3%.

However, it was weakness in the financial sector that hampered the broader market. Financials, which make up 14% of the stock market's weight, fell 1.8%.

Pressure against financials followed several headlines, which began with news that Citigroup (C 3.20, -0.25) priced shares in its previously announced common stock offering at $3.15 each, a near 9% discount to the previous session's closing price. The low price tag even kept the Treasury from unloading its $5 billion of shares in the company.

Shares of investment banks and brokerages were sent to a 2.8% loss after highly regarded analyst Meredith Whitney lowered her earnings estimates for Morgan Stanley (MS 29.12, -1.22) and Goldman Sachs (GS 160.93, -4.06).

2:02AM On The Wires : Giga-tronics (GIGA) announces that it has received three orders valued at $5.1 million for microwave components from a major aircraft manufacturer... Nokia (NOK) and ST-Ericsson (ERIC) announce a long-term partnership in the area of TD-SCDMA technology and solutions.