UPDATED POST WITH CLOSING PRICES: Investor reaction to the collapse of a joint venture between Dow Chemical Co. and Kuwaiti interests was swift and certain today.

Dow Chemical shares closed at $15.32, down 19 percent, or $3.60. That's a big move on a day during a holiday week when the Standard & Poor's 500 Index was down less than 1 percent. Dow Chemical was the biggest loser among the S&P 500.

The swoon in Dow Chemical shares has also exerted a downward pull on Philadelphia's Rohm & Haas Co., which Dow agreed to buy in July in an all-cash deal worth $15.2 billion.

Shares of Rohm & Haas closed down 16 percent, or $10.22, at $53.34. Today is the seventh straight trading session that Rohm & Haas shares have fallen since hitting $70.50 on Dec. 17.

An analyst from Deutsche Banc speculated today that the $78 price Dow Chemical agreed to pay Rohm & Haas shareholders may be renegotiated lower. However, another at Barclays says that the chemical giant has enough in bridge loans to close the deal.