The NPD Group estimates that downloadable, social, mobile and other form of non-physical games took up to $400m in sales last month.
The research firm's data shows that hardware and boxed sales were down 34 per cent year-on-year in January – coincidentally also around the $400m mark.
NPD analyst Liam Callahan said: "Outside of new physical retail sales, we estimate that the consumer spend on other ways to acquire content including used games, full game and add-on content downloads, social network games, mobile games, rentals and subscriptions accounted for an additional $350m to $400m in sales."
This echoes the situation in the UK, where the games market value fell by 13 per cent in 2011 – a deceptive number given that this figure only takes retail sales into account.
Geoff Heath, part of the UKIE group behind the digital charts due this month, told us last month that this does not represent the true games market value. Heath was one of several experts that have been vocal about the need for digital charts.
MCV has called for the industry to support the sharing of digital sales data.