Conventional watch sales slide after Apple Watch launch, NPD says

Unit sales were down 14 percent year-over-year to about 927,500, the harshest decline since 2008, NPD told Bloomberg. Retail revenue slid by 11 percent to $375 million.

The head of NPD's luxury division, Fred Levin, noted that watches costing less than $1,000 were most likely to be impacted by the Apple Watch, since that's the range in which people have said they're most likely to buy Apple's product. Indeed watches costing between $50 and $999 suffered setbacks in June, although the most damage came in the form a 24 percent drop for pieces costing between $100 and $150.

Lower-cost brands like Timex, Burberry, and Tissot did poorly during the month, as retailers tried to use discounts to combat consumer saturation.

The true impact of the Apple Watch is difficult to gauge, mostly because Apple has refused to share exact sales numbers or even break out Watch revenue reporting into its own category. Bloomberg remarked, though, that since the category containing the Watch gained $950 million within the product's first quarter, Apple presumably sold at least 1.9 million units, assuming an average selling price of $499.

Unmentioned by NPD is what impact other smartwatches might be having. Although devices from the likes of Pebble, Garmin, and Motorola have had relatively modest success, they could be doing well enough to eat into conventional watch sales.