U.S. stock markets are primed for big losses today following declines in both Asia and Europe. As of 7:15 a.m. EDT, futures for the Dow Jones Industrial Average (^DJI 0.69%) suggest that the index will fall 0.86% at the open, while the S&P 500 (^GSPC 1.20%) may open 0.95% lower.

The Shanghai Composite dropped an incredible 5.3% today as high interbank rates made investors fear a liquidity crunch in the world's second-largest economy. Goldman Sachs also lowered its growth expectations for China from 7.8% to 7.4% in 2013 and from 8.4% to 7.7% in 2014. China has been one of the few economies growing more than a nominal amount over the past five years, so slower growth would have a negative impact on economies worldwide. 

Europe is feeling the pressure from China, and all European stock markets are down 1% or more as of 8:10 a.m. EDT. But not everything in the market is so bearish today.

Companies are still looking for ways to expand, and there are a few acquisitions that should give investors a little hope. Vodafone (VOD 0.81%) agreed to buy Kabel Deutschland, Germany's largest cable operator, for $10.1 billion in an effort to expand in one of Europe's only healthy economies. Vodafone will expand its TV and fixed-line business and add them to the wireless services it already offers in the country.  

Tenet Healthcare (THC 3.17%) has agreed to pay $1.63 billion for Vanguard Health Systems (NYSE: VHS), a 70% premium to Vanguard's close on Friday. The deal will diversify Tenet's offerings in acute care and specialty hospitals and give it a wider geographic reach as well. Tenet is up 8.4% in premarket trading, while Vanguard has skyrocketed 64%. 

Foolish bottom line
It doesn't look like a strong start to the week on Wall Street, and investors should be concerned about slowing growth in China. It's been one of the bright spots in the global economy, and slower growth will put pressure on the U.S. and Europe to pick up the slack or risk another recession.

Long-term investors should keep in mind that the day-to-day fluctuations on Wall Street don't impact the fundamental value of great companies, and a huge gain can come at any time. Vanguard's 70% premium is a prime example of that.