Telecommunications software maker

Vertel

(VRTL)

was down 5.9% in early afternoon.

The move was apparently triggered by the resignation of Bruce Brown as chairman. He also left the board of directors. Brown is also president and chief exec of Internet routing equipment maker

Efficient Networks Inc.

(EFNT)

. Efficient was up 1.14%.

Vertel said it will return to its earlier structure, operating without a chairman.