GROUP RAISES TEXSTYRENE <FOAM> STAKE TO 11.7 PCT An investor group led by Dart Container Corp, a Sarasota, Fla., plastic utensil maker, told the Securities and Exchange Commission it raised its stake in Texstyrene Corp to 420,500 common shares or 11.7 of the total outstanding. The group said it bought the shares for investment and intends to continue to buy Texstyrene stock in the future. The group said its most recent purchases included 106,000 shares bought March 10-31 in ordinary brokerage transactions.