By Alexandra Gibbs, CNBC–

U.S. stock index futures tumbled deep into the red ahead of Wednesday’s open, as global trade fears added jitters across markets around the world.

Around 5:30 a.m. ET, Dow futures fell 138 points, indicating a negative open of 112.11 points. The Nasdaq and the S&P 500 futures indicated a downbeat start to their respective trading sessions.

Markets around the world have been on a rollercoaster ride in recent weeks as fears around trade tensions between the U.S. and other major economies escalate. Not only is the U.S. in a tit-for-tat war of words with China on tariffs, but now the European Union is involved.

Last week, President Donald Trump threatened a 20 percent tariff on all car imports from the EU. He added that if the EU chose not to remove its duties on American vehicles, then the U.S. would have no choice but to act on those levies.

Trade tensions have since ratcheted up another notch this week following reports that Washington intended on blocking some Chinese businesses from investing in U.S. technology. However, Treasury Secretary Steven Mnuchin called the reports “fake news.”

On Tuesday, Washington chose to ramp up the pressure again, this time on the oil sector. A senior official from the State Department told reporters that businesses that purchase Iranian crude oil must cut those exports entirely by the beginning of November — or face sanctions. Consequently, markets are on edge during Wednesday’s session.

While political news is expected to keep investors busy, in economic data, mortgage applications are due at 7 a.m. ET, followed by durable goods and advanced economic indicators at 8:30 a.m. ET, and pending home sales data at 10 a.m. ET.

On the corporate front, among the companies set to publish earnings are General Mills, Paychex, Bed Bath & Beyond, Pier 1 Imports and Rite Aid

In addition, investors will be watching what the trade tensions could mean for corporates. On Tuesday, Trump threatened Harley-Davidson that it would be “taxed like never before” if it chose to move its production to outside of the U.S.

In central banking news, Boston Fed President Eric Rosengren will be in Washington at the 2018 Annual O. John Olcay Lecture on Ethics and Economics at the Peterson Institute for International Economics. In Idaho, Fed Vice Chairman of Supervision Randal Quarles is expected to attend the Utah Bankers Association 110th annual convention.