US stocks mixed as investors brace for a 50-basis-point rate hike from the Federal Reserve

• US stocks opened mixed Wednesday ahead of a decision from the Federal Reserve's policy meeting.
• The Fed is expected to raise interest rates by 50 basis points, which would be the largest rate hike since 2000.

Stocks opened mixed Wednesday as investors braced for the Federal Reserve's biggest increase in interest rates in more than 20 years as it combats decades-high inflation.

Wednesday's main event lies with the Fed, which is slated to release its latest policy decision at 2 p.m. ET followed by a press conference at 2:30 p.m. with Chairman Jerome Powell. Fed funds futures have priced in a 97.9% chance that the central bank will raise interest rates by 50 basis points, or 0.5 percentage point. That would be the largest rate hike since 2000 and increase the Fed's key interest-rate range to 0.75%-1%.

"The Federal Reserve is in a tough spot right now as it navigates elevated risks of a recession. [Policy makers] want to raise rates high enough and fast enough to curb inflation, but they don't want to tip the economy into a recession," said John Leer, chief economist at market research firm Morning Consult, said in a note.

Consumer price inflation accelerated to 8.5% in March, the fastest increase since December 1981.

Here's where US indexes stood at 9:30 a.m. on Wednesday:

• S&P 500: 4,178.16, up 0.6%
• Dow Jones Industrial Average: 33,161.15, up 0.10% (32.36 points)
• Nasdaq Composite: 12,555.32, down 0.07%

The Fed is also expected to outline its plan to reduce its balance sheet, starting with reducing asset purchases by $95 billion a month in June.

"Looking ahead, markets still have a lot of new information to process in the coming days. Even after we hear from Chairman Powell on Wednesday, so much will be riding on the April jobs report out on Friday and the CPI out next Wednesday. A serious miss on either front exposes markets to further corrections, which in turn could weigh on the real economy," said Leer.

ADP said Wednesday that private employers in the US added 247,000 jobs in April, significantly less than the 395,000 expected in a Bloomberg survey of economists. April's figure reflects slower growth from March and marks the smallest monthly gain since August.

Around the markets, oil prices climbed after the European Union unveiled a long-awaited proposal that would phase out imports of Russian crude in six months. The EU move adds to sanctions placed on Russia for launching a war against Ukraine in late February.

West Texas Intermediate crude gained 4.4% to $106.90 per barrel. Brent crude, the international benchmark, jumped 4.2% to $109.42.

Elon Musk, who is in the midst of buying Twitter, has begun telling investors that they could probably cash out through a public offering for the company in as little as three years, according to a Wall Street Journal report.

Gold slipped 0.9% to $1,869 per ounce. The 10-year yield rose 2 basis points to 2.98%.

Bitcoin gained 3.7% at $39,033.51.