GameStop shares fell 8.8 percent today, 17.2 percent since Xbox One announcement

Shares of GameStop closed down 8.8 percent today (from $35.20 to $32.11) and 17.2 percent since the beginning of the week (where it began at $38.76) in the wake of the Xbox One reveal.

For comparison, GameStop shares closed at $25.50 on Tuesday, Feb. 19 (markets were closed on Feb. 19 for President's Day, the day before Sony unveiled the PlayStation 4). On the Friday following Sony's PlayStation 4 announcement, Feb. 22, shares closed at $24.82, a decrease of 2.7 percent. Nintendo revealed the Wii U on June 5, 2012, during E3. On that Monday, June 4, GameStop stock closed at $19.20. On Friday, June 8, it closed at $19.03, a decrease of 0.9 percent.

A possible reason for this week's disproportionate decrease in GameStop's share price could be the still-uncertain future of used games on Xbox One. Following the console's reveal this week, a report surfaced saying that the console would charge players a fee to play used games. Microsoft later characterized the reports as "potential scenarios." Sources tell Polygon that Microsoft has no plans to charge a fee to sell or reactivate games.

Yesterday, GameStop revealed sales of $1.87 billion in Q1 2013, a 6.8 percent decrease from the same period last year. Mobile sales increased 290 percent, while sales of pre-owned goods dropped 7.5 percent.

For GameStop's take on Sony and Microsoft's next-gen consoles, be sure to check out Polygon's interview with the retailer's president, Tony Bartel, conducted shortly after the Xbox One announcement.