The summer market turmoil is a perfect storm for the world's biggest luxury brands

Nothing is going quite right for the world's major luxury goods brands at the moment.

The market tumult that began in China and ripped through Europe and the Americas is particularly bad for some companies, and there's no question that major producers of fashion items, watches and jewellery are among them.

A HSBC note released on Wednesday gives the main reasons for that, explaining why stock prices for these major brands have been even weaker over the past month than other big listed companies.

A chart from the research note shows that altogether, major luxury stocks are actually in a bear market - taken from their various highs over the course of 2015 so far they're down 22.4% today. All taken from the 10th of August to Monday, they're down 15.9%.

Here's how it looks:

There are two big problems for big luxury goods exporters.

The first is the euro, which has appreciated considerably in August. It's currently sitting at just below $1.15. The European single currency is strengthening as markets panic, prompting some people to ask if it's the new safe haven currency.

Since the luxury exporters are largely based in Europe, that's not good news. A stronger euro means it effectively costs US consumers more to get hold of European goods.

Earlier in the year, people were talking seriously about the euro going to parity against the dollar by the end of 2015, or even lower, but at the moment that looks far less likely to happen.

The second problem is China, which was once a massive tailwind for luxury retailers. While European and American economies were in recession or stagnating after the financial crisis, the rise of the Chinese upper-middle class continued apace, with more cash to spend than ever.

Now, it's more of a worry. Chinese disposable income is still rising, but the economy is growing at its slowest pace in decades. The government's control over the economy is coming under increased scrutiny, with the stock market plunging.

What's more, the depreciation of the yuan last week is a nerve-wracking experience for any major exporters to China - as with the euro-dollar exchange rate, if the euro strengthens against the yuan it makes it harder for anyone on a yuan income to afford luxury products - and in worrying economic times, those expensive but ultimately discretionary purchases are the first sort of thing people cut back on.