The VN-Index opened higher Tuesday, briefly dipped into the red in morning trading before climbing early in the afternoon to 677, a level that, had the index closed there, would have been a fresh eight-year high. However, in less than an hour of the afternoon session, the market plunged 2.5% to 660 before rebounding to close down 5.74 points, or 0.9%, at 667.76.