Nintendo shares briefly lost one-fifth of their value on Monday as investors reacted to a drastic profit warning issued by the company last week.

Nintendo (NTDOF) said Friday that it expects an operating loss of 35 billion yen ($335.2 million) for the fiscal year ending in March, following disappointing software and hardware sales in the busy end-of-year buying season.

That's a significant downturn from the profit of 100 billion yen ($957.7 million) previously forecast. The electronics maker also slashed estimated figures for global sales of its Wii U console to 2.8 million from 9 million, even after it cut the price of the device last year in a bid to draw buyers.

Nintendo shares in Tokyo pared some morning losses, but closed more than 6% lower on the day.

The Wii U has struggled to lure consumers as the appetite for mobile and tablet gaming grows, underscoring problems with the company's strategy and ability to keep up with gaming trends.

Related: Nintendo's big problem

Stiff competition from rival devices -- Microsoft's Xbox and Sony's PlayStation -- has also hurt Nintendo. Microsoft (MSFT) and Sony (SNE) have turned their gaming consoles into integrated, computing devices, and new models of the devices released late last year were in hot demand.

At the same time, Nintendo, maker of a string of best-selling games including Mario Bros. and Wii Fit, has shied away from online gaming and entertainment-based features.

Nintendo shares got a boost earlier this month when China loosened restrictions on video game consoles. The new market could be a boon for Nintendo, but it's not yet clear whether the company will embrace the experiment.