Well, that didn’t last long.

Garmin (GRMN) shares, which traded higher early this morning on a stronger-than-expected Q3 financial report, then gradually moved lower as the market opened, have taken a hit in the wake of the company’s post-earnings conference call with the Street.

The company did not give any specific Q4 guidance on the call, but it did say it expects unit shipments of personal navigation devices to increase 40%-50% in the quarter, but with lower pricing and margins than it experienced in the third quarter. That’s in contrast to a surprise jump in average prices and margins in Q3, thanks to the introduction of some new products. Garmin also said it expects the fitness segment to be flat year-over-year in the quarter, with weakness in aviation; marine segment revenues are expected to be down sequentially in Q4 due to seasonality.

The company said full ASP decline in PNDs will be 15%-20% for the full year, which implies lower prices than in the third quarter.

GRMN is now down $3.85, or 12.3%, to $27.56.