A growing number of companies are flashing a warning sign on China's economy

Samsung Electronics on Wednesday estimated that its profit in the last three months of 2018 was down nearly a third from the previous year's. It cited "lackluster" demand for what would mark its first quarterly decline in two years. The company’s market share for smartphones in China has slumped to less than 1%.

"Depressed demand in China will further drive down Samsung's chip sales there," Song Myung-sup, a senior analyst at HI Investment & Securities, told Reuters. And China's overall smartphone market is stalled and declining, which will affect not only Apple but Samsung."

China is the second-largest market for Starbucks after the US, growing consistently. But that could become a problem when consumer demand fizzles. As a luxury brand in China, the coffee company is particularly vulnerable to economic conditions.

Bloomberg reported last month that Starbucks CFO Patrick Grismer said same-stores sales growth in China, a closely-watched indicator in the restaurant industry, could fall to as low as 1% in the long-run.

Slowing Chinese tourism and spending in the US and Hong Kong contributed to Tiffany’s lower sales in the third quarter, the company said in November.

While sales in mainland China held up, according to the release, CEO Alessandro Bogliolo said in an earnings call the company had "clearly seen" a shift in Chinese tourism and spending.

HP CEO Dion Weisler underlined the importance of China as a market in November, CNBC reported, and said the company was monitoring business conditions there.

"We obviously continue to assess the situation and the potential impact on our business and our plans that we may or may not need to make as a result — but again, we're not chasing ghosts, but we're also not sticking our heads in the sand either," he said of the trade war.

Daimler blamed rising protectionism as it cut its profit forecast twice last year, warning that tariffs would have a negative impact on sales. The German carmaker had already been expecting Mercedes-Benz sales in China to slow.

While China moved to lower its tariff on vehicles in December, trade tensions have added a layer of uncertainty on top of already waning automotive demand in the country.