Tesco and Asda have both lost share in the entertainment market, as Amazon reinforces its dominance.

Figures for the second quarter of 2012 showed Tesco’s market share has dropped 1.7 percentage points year-on-year to 10.7%, while Asda slipped 0.2 points to 8.3% [Kantar Worldpanel].

Amazon, boosted by strong growth in ebook sales, now holds 21.4% of the market – more than Tesco and Asda combined.

It wasn’t all bad news for the supermarkets, however. Sainsbury’s and Morrisons both increased their share by 0.4 points, to 5.3% and 3.3% respectively.

Despite its dip, Tesco has maintained its advantage over the other supermarkets, accounting for 36% of physical sales of video, music and games through the big four retailers, and 73% of online sales.

“The major losses to grocers have come though falling buyer numbers, which have dropped by 20%,” said consumer insight director Kantar Fiona Keenan.

“The majority of these lost buyers are category departures – past shoppers who didn’t buy music, video or games products through any retailer during the quarter.”

Much of Amazon’s growth has been at the expense of specialists such as second-placed HMV, which has lost 0.8 point of share since last year – opening up the gap between it and Amazon to 4.8 points.

“While grocers have also lost some share to internet retailers, their shoppers are less engaged in the online channel than the average entertainment consumer and less likely to switch to online,” added Keenan.

Game Group – which closed 277 Game and Gamestation stores earlier this year – lost half its market share, dropping from 10% to 5.2%.