I’ve been warning of luxury slowdown throughout the summer. And the reason can be explained in a single word: China.

For the past three years, China and Chinese tourists shopping abroad have filled the gap in the luxury market left by the Americans and Europeans. China is now the world’s second largest market for luxury goods, behind Japan. Despite the current slowdown in China's economy, the country's luxury market is expected to top $12 billion this year.

But that support may be slipping . After Burberry's earnings warning this morning, it's stock fell 18 percent. Other lux stocks fell in sympathy, including LVMH, Hermes and Richemont.

It's unfair to lump these all of these companies together, especially as the luxury market bifurcates into strong high-end brands and weaker mass-luxury marketers. And some are run better than others. Hermes, for example, should not be punished for the retail strategies of Coach and Burberry.

But all of these luxury companies share a common problem. They have all become dependent on China. And China is slowing. (Read more: Long Luxury Boom Slows in China )

As David Faber said on our air this morning: “Chinese high rollers are just not rolling as high.” China's next leader is missing, and so is China's luxury consumer.

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