WASHINGTON (Reuters) - Negotiators reached a phased deal on Wednesday to end the war in Gaza between Israel and Hamas, an official briefed on the negotiations said, after 15 months of conflict that has killed tens of thousands of Palestinians and inflamed the Middle East.

The accord, which has not yet been formally announced, outlines a six-week initial ceasefire phase and includes the gradual withdrawal of Israeli forces from the Gaza Strip and release of hostages held by Hamas in exchange for Palestinian prisoners held by Israel, the official told Reuters.

Here are some investor and analyst reactions to the deal:

ART HOGAN, CHIEF MARKET STRATEGIST, B. RILEY WEALTH, NEW YORK

"It's clearly an unambiguous positive for the markets and certainly for global markets. I think it's going to take a bit longer for this to settle in to the news flow, especially in a market that was already up, but this is clearly something that will prove to be an unambiguous positive."

"The overarching positive of all of this will likely start settling in the weeks to come, and not necessarily this afternoon."

SAM STOVALL, CHIEF INVESTMENT STRATEGIST, CFRA RESEARCH, NEW YORK

"Since geopolitical tensions are one of the bricks in this wall of worry that the market is climbing, it's good to have at least one source removed. The only question is whether this can be extended, since tensions always seem to flare up in the Middle East."

"Investors now have more than one reason to breathe a sigh of relief today after the CPI data and this news from Gaza. Stock market headwinds are less of a hurricane and more of a gentle breeze."

MICHAEL BROWN, SENIOR RESEARCH STRATEGIST, PEPPERSTONE, LONDON

"This news was very much expected and had been hinted at quite strongly in recent sessions so shan't have come as a surprise to most participants."

"I suppose at the margin it reduces geopolitical risk to a degree, though the question now is how long the ceasefire holds for. The situation in the Middle East, as ever, is a precarious and volatile one, so I doubt anyone will be rushing to buy risk or unwind their safe haven hedges just yet - certainly not with Trump's inauguration on Monday looming large on the horizon."

CHUCK CARLSON, CHIEF EXECUTIVE OFFICER, HORIZON INVESTMENT SERVICES, HAMMOND, INDIANA

"Some of it had already been telegraphed in the market, so I don't think it was a complete surprise... If there is any significant impact, it will be an influence on the energy complex."