Nortel Networks stock plunged Wednesday morning and dragged Toronto’s S&P/TSX index into triple-digit losses after the firing of three top executives, including CEO Frank Dunn.

Nortel shares tumbled $2.03 or 26.78% to $5.55 after the company announced that Dunn, the firm’s chief financial officer and its controller — both of whom had been on paid leave of absence since March 15 — were fired “for cause.”

The company added that it will slash its 2003 earnings in half after a recent reassessment.

Nortel, the most heavily weighted stock on the Toronto Stock Exchange, has pushed the S&P/TSX composite index down 2.55%, or 217.35 points, to 8,317.67 in mid-morning trading..