Navigational device maker TomTom said today that it plans to raise its bid to acquire digital-map provider Tele Atlas in order to trump a competing offer from Garmin . TomTom's new offer is for 30 euros per share, well beyond Garmin's 24.50 euros-per-share offer. The new price represents a premium of more than 80% to Tele Atlas's closing price on July 20, which is when TomTom first extended its buyout offer.

The shares of Garmin are down more than 6% in pre-market trading to hover above the 100 level. The stock breached support from its 10-week moving average last week amid news of the bidding war, and GRMN is now relying on its 20-week trendline to lift it higher.

Even as the equity has slipped, option-trader sentiment has turned bullish. GRMN's Schaeffer's put/call open interest ratio checks in at 0.81, near the middle of its annual range and markedly lower than its week-ago reading of 1.07, in the 86th annual percentile.