Major announcements by tech giants of new artificial intelligence offerings helped lift US stocks Tuesday, following a rollercoaster session that included Federal Reserve comments viewed as muted on inflation.

Both Microsoft and Google parent Alphabet jumped more than four percent after product announcements in what Microsoft CEO Satya Nadella called a technology "race" -- boosting US indices on a mixed day for global stocks.

"This technology is going to reshape pretty much every software category," Nadella added at an event at Microsoft's Redmond, Washington, headquarters that showcased how its long-struggling Bing search engine will integrate the powerful capabilities of language-based artificial intelligence.

All three major US indices finished higher, led by the tech-rich Nasdaq, which jumped nearly two percent.

Stocks had earlier gyrated on comments from Fed Chair Jerome Powell in his first public appearance after Friday's blowout US jobs report, which revived worries about a prolonged US central bank campaign to counter inflation.

On Tuesday, Powell said US inflation is starting to cool but the road ahead will likely be long and bumpy.

Powell expects 2023 to be a year of "significant declines in inflation," but that the figure will only come down close to officials' two percent target next year.

"The labor market's extraordinarily strong," Powell said, adding that it was good that inflation is coming down while not at the cost of a robust jobs market.

Analysts saw Powell's tone as not significantly different from last week, which markets viewed as benign.

"Powell's tone was a bit friendlier and I think the market interpreted that as a dovish sign," said Steve Sosnick, chief strategist at Interactive Brokers.

Tuesday's rally in New York comes ahead of President Joe Biden's annual State of the Union address, at which he is expected to highlight the resilient jobs market and progress in mitigating inflation.

In Europe, Paris and Frankfurt finished lower while London was up. Hong Kong and mainland Chinese indices closed higher while Tokyo was flat.

- Bounce for Adani -

London's FTSE 100 was boosted Tuesday by bumper annual profits from British energy giant BP, whose shares soared by seven percent.

Sydney dropped Tuesday as the Australian central bank hiked interest rates to a 10-year high and warned of more to come as it struggles to get a hold on inflation.

Mumbai was also on the back foot, though shares in tycoon Gautam Adani's troubled empire soared following news it had moved to pay back loans of $1.1 billion, after allegations of accounting fraud wiped more than $100 billion off the group's market value.

Adani Enterprises jumped as much as 25 percent before trading was suspended. They then pared some of those gains when they restarted.

In other markets, oil prices rose for a second day after Iraqi Kurdistan suspended crude exports through Turkey as a precaution, following a deadly earthquake that rocked its northern neighbor and Syria.

Analysts also pointed to strengthening demand in China as a source of upward pressure on crude prices.

- Key figures around 2130 GMT -

New York - Dow: UP 0.8 percent at 34,156.69 (close)

New York - S&P 500: UP 1.3 percent at 4,164.00 (close)

New York - Nasdaq: UP 1.9 percent at 12,113.79 (close)

London - FTSE 100: UP 0.4 percent at 7,864.71 (close)

Frankfurt - DAX: DOWN 0.2 percent at 15,320.88 (close)

Paris - CAC 40: DOWN 0.1 at 7,132.35 (close)

EURO STOXX 50: UP 0.1 percent at 4,209.31 (close)

Tokyo - Nikkei 225: FLAT at 27,685.47 (close)

Hong Kong - Hang Seng Index: UP 0.4 percent at 21,298.70 (close)

Shanghai - Composite: UP 0.3 percent at 3,248.09 (close)

Euro/dollar: UP at $1.0732 from $1.0726 on Monday

Pound/dollar: UP at $1.2043 from $1.2019

Euro/pound: DOWN at 89.03 pence from 89.24 pence

Dollar/yen: DOWN at 131.07 yen from 132.66 yen

Brent North Sea crude: UP 3.3 percent at $83.69 per barrel

West Texas Intermediate: UP 4.1 percent at $77.14 per barrel