It is VERY likely that AAPL has become the largest watch 'brand' in the world, as measured by revenue. During its September 2016 special event when it launched the iPhone 7 / 7 Plus, as well as the AAPL Watch Series 2, AAPL CEO, Tim Cook, put up a very interesting slide. It showed AAPL as the second largest watch brand in the world, as measured by revenue, just behind Rolex for 2015 - a year in which AAPL only shipped watches for 9 months. I believe that slide needs to be adjusted:
After looking at the numbers and relying on some very intelligent analysts who have put forth reasonable quarterly estimates on AAPL Watch shipments for the past four quarters (June 2016 through March 2017), it is very easy to conclude that AAPL has overtaken Rolex in TTM revenue, and by a rather large margin - approximately $650 million. Rolex revenue has been stagnant and estimates have pegged its annual revenues at $4.5 billion to $4.7 billion, annually.
Further to this assertion is commentary that was recently provided by AAPL Management when discussing its Fiscal Q2 earnings:
Cook on state of the Watch product:
"Apple Watch sales nearly doubled year over year. Apple Watch is the best-selling and most loved smartwatch in the world, and we hear wonderful stories from our customers about its impact on their fitness and health."
"We have seen the watch as a really key product category for us since before we launched it. We took our time to get it right, and we've made it even better with the Series 2 offering. And we're really proud of the growth of the business. The watch units more than doubled in six of our top ten markets, which is phenomenal growth, particularly in a non-holiday quarter. And so we couldn't be more satisfied with it."
It is important to note that AAPL is likely the largest watch BRAND as measured by revenue, but it is not the largest WATCHMAKER by revenue. The consolidation of watch brands under one company has created conglomerates like Swatch, which includes the Swatch brand, Omega, and Breguet (just to name a few). The luxury brand conglomerate LVMH has a number of luxury watch brands including Hublot, Bulgari, Zenith and Tag Heuer.