Wall Street stocks ended little changed on Wednesday after the Federal Reserve kept interest rates steady, while markets followed the ongoing fighting between Iran and Israel.

The Fed, as expected, held interest rates unchanged for a fourth consecutive meeting, as Chair Jerome Powell said more time was needed to monitor the inflationary effects of US President Donald Trump's tariffs.

Meanwhile, Trump told reporters he has not yet made a decision on whether to join Israel in bombing Iran.

Stocks spent part of the day in positive territory, but the Dow Jones ended down 0.1 percent at 42,171.

The S&P 500 slipped less than 0.1 percent to 5,980, while the Nasdaq added 0.1 percent at 19,546.

The market's ability to avoid major losses amid the Middle East turmoil is "extremely bullish," said Adam Sarhan of 50 Park Investments, while still pointing to trade-talk uncertainty as a worry.

The market believes that "most likely cooler heads will prevail on the trade front and on the Middle East front," said Sarhan, who described Wednesday's Fed meeting outcome as in line with expectations.

Shares of Visa and Mastercard both fell about five percent after the US Senate approved a bill to regulate stablecoins – cryptocurrencies pegged to assets like the dollar – in a move that could make them more attractive to investors.

The growth of the newer means of exchange has been seen as a threat to traditional payment methods embodied by the credit card companies and by PayPal, which also fell.

Coinbase surged 16.3 percent. (AFP)