March 17 (Reuters) - Athletic apparel maker Lululemon forecast 2026 revenue and profit below Wall Street expectations on Tuesday, underscoring its challenges as it faces rising competition and an attempt by founder Chip Wilson to overhaul the board.

Its shares fell 2.4% in extended trading.

Upheaval at Lululemon follows months of share price weakness and lack of design freshness, culminating in CEO Calvin McDonald's departure in December and a subsequent proxy fight by its founder.

Once a pioneer of the athleisure category, the company also lost ground to big sportswear brands like Nike as well as upstarts such as Alo Yoga and Vuori.

Lululemon expects annual revenue to be between $11.35 billion and $11.50 billion, compared with analysts' average estimate of $11.51 billion, according to data compiled by LSEG.

It also forecast annual profit in the range of $12.10 to $12.30 per share, while analysts estimated $12.58.