The S&P/ASX 200 Index (ASX: XJO) has battled its way back from a 0.7% loss this morning to be down 0.1% at the time of writing in the early afternoon on Wednesday.

With United States President Donald Trump's sweeping tariffs opening the door to a global trade war and with hostilities in Gaza and Ukraine appearing increasingly likely to continue over the medium term, there's been no shortage of volatility in global stock markets.

And the ASX 200 is no exception, with the benchmark Aussie index still down 8.2% since the recent highs on 14 February.

Now, here's why tomorrow could be a big day for ASX shares.

What could move the ASX 200 on Thursday? 

When ASX 200 shares start trading tomorrow, we'll know the outcome of the US Federal Reserve's latest interest rate decision.

Following three rate cuts in the latter months of 2024, the official Fed funds rate stands at 4.25% to 4.50%, down from 5.25% to 5.50% last August.

With markets pricing in only a 1% chance that the Fed will cut at tonight's meeting, a surprise rate reduction would likely spur a big rally on the ASX 200. Stocks could also get a lift if rates remain on hold, but Federal Reserve chair Jerome Powell offers a dovish outlook for future cuts in the world's biggest economy.

"In the US this week, a rate cut following the FOMC's meeting on March 19th is not looking likely, following recent volatility and market uncertainty thanks to President Trump's tariffs," Josh Gilbert, market analyst at eToro, said.

Noting that Powell has previously indicated that the Fed can afford to be patient when adjusting interest rates, Gilbert added:

With tariffs set to make a number of products more expensive for Americans, the Federal Reserve is likely to be on close watch as the repercussions of Trump's tariffs become evident over the next few months.

If trade war tensions continue to escalate, the view of no rate cuts this year remains a real possibility.

What else is happening on Thursday?

The ASX 200 also could be impacted by the latest Aussie unemployment data covering the month of February. That's due out late morning tomorrow.

Australia's unemployment figure has held at a fairly constant, and historically low, 4% for the past months now.

If tomorrow's data shows that the jobs market remains strong, with unemployment levels potentially falling, it could mean ASX 200 investors will be waiting longer than hoped for the next interest rate cut from the Reserve Bank of Australia (RBA).

According to Gilbert:

Last month's RBA rate cut, a significant milestone after a long period under a cost-of-living crunch, may pull this month's unemployment figure lower – and almost certainly will have an impact on the March figures set to be released next month.

That reduction would be a welcome sign for jobseekers but a concern for economists, as a healthy jobs market could stoke the flames of inflation once more.

Stay tuned!