Apple generated a ton of buzz leading up to the release of its debut wearable. The campaign effort led to an early pop in sales that quickly put the Cupertino-based company ahead in a market that nobody has yet found traction in.

Data from research firm Slice Intelligence reveals that once pre-orders had been filled, sales held steady through May and into early June before taking a turn for the worse.

According to Slice, sales have plunged by 90 percent since opening week. That's a bit skewed due to pre-orders but still, the trend is quite grim as Apple had reportedly been selling around 20,000 units per day in the US during May and early June, but later in the month that figure has dropped consistently to well below 5,000 units.

The firm points out that two-thirds of Apple Watch sales have been of the lower-profit Sport version which starts at $349. Slice also contends that fewer than 2,000 of the premium Watch Edition have been sold in the US since launch. Pricing for the Watch Edition starts at $10,000.

IHS Technology recently found that the Apple Watch Sport has the best profit margin of any Apple product with an estimated cost to build of just $83.70. It's worth reiterating that these are unofficial numbers since Apple has yet to reveal official sales figures. The company will likely announce those in its next earnings report on July 21.