Nintendo has reported a larger second-quarter loss than expected, causing a fall in its share price.
The Japanese firm posted a 9.9 billion yen (£57 million) loss for the April to June months, compared with a 8.6 billion yen profit for the same period 12 months ago.
Despite the release of Mario Kart 8 in May, sales were 8 per cent lower compared with last year.
However, the firm did not change its prediction for a full-year profit, despite falling to a loss in the previous financial year.
The company stated that it was still optimistic that key releases in the run-up to the Christmas-period, particularly its Super Smash Bros fighting game, would boost demand.
While Nintendo won praise for the innovative titles revealed during June's E3 video games expo, including the next instalment in its successful Legend of Zelda franchise, some analysts suggest that the firm's problems are bigger than anticipated.
"They have a relatively good games pipeline, but the big question is about its hardware," said Ed Barton, a games industry analyst at the Ovum consultancy.
"The Wii U is so far behind now, and the perception of the audience that it's a relatively under-powered console compared to the PlayStation 4 and Xbox One is now pretty firmly cemented."
Nintendo originally forecast it would sell nine million Wii Us during the last financial year, but despite a price cut, the company only managed to shift 2.7 million units.
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Documents posted online also revealed that Nintendo's total assets fell by 6 per cent over the last quarter, taking them to about $12 billion (£7.1 billion). The news prompted a fall in the firm's share price of around 6 per cent from its opening price on the Frankfurt Stock Exchange.