Shares in athletic clothing company Under Armour have plunged 14%, despite the company increasing its forecast revenues and earnings for FY 2007.

Under Armour blamed a shift in marketing spend to the first half of 2008 for its forecast first half diluted EPS of US$0.03-0.05, well down on analyst expectations.

The company has booked a 60-second TV slot on Superbowl night to push its new Performance Training footwear line.

Under Armour's full year 2007 net revenues are now expected to rise 40% to an estimated $605m, ahead of previous guidance of $590-600m, the company said. Income should exceed previous estimates of $81.5-83m, it added, yielding diluted EPS of $1.03-1.04.

The company reiterated its belief that 2008 net revenues and income from operations would exceed long-term growth targets of 20-25%.

The Superbowl ad, which airs on 3 February, is part of a year-long campaign to launch the Performance Training range. But its timing meant a "substantial" shift of marketing expenses into the first half, Under Armour said.

"We believe the launch of our performance trainers is critical to the long-term foundation of the Under Armour growth story," said chairman and CEO Kevin Plank.

"We are confident that our innovative technology, driven by insight from athletes, combined with the consumer demand this campaign is generating, will ensure its success."

Under Armour is due to report its fourth quarter and full year results on 31 January.