Wii U software sales are "struggling a bit" in the US, according to Cowen & Company analyst Doug Creutz.
Reacting to last night's release of NPD sales data for the US market in December, Cowen said in a research note: "Software sales for the Wii U remained well behind launch levels for the original Wii and GameCube in December.
"Totals for the November-December period were -43% lower than software sales for the Wii and -50% lower than those for the GameCube."
The relatively low Wii U software sales appear to have been masked somewhat by news of the revenue generated by the platform since launch.
North American Wii U unit sales during the console's first full month failed to match those set by the Wii in December 2006, though the new system has generated more revenue in the same time frame.
Taking Wii U's relatively low software sales into account, it appears that the system's higher launch price ($300 for Basic model/$350 for Premium, compared to Wii's $250) was the main reason the new console's launch revenue exceeding its predecessor.
In the UK, no exclusive Wii U game has entered into the top 40 all format chart for the past three weeks.
Following last night's announcement of the Wii U sales results, Nintendo's stock climbed 5.6 percent in Osaka trading to close at 9,070 yen, its biggest gain since September 18.