US STOCKS-Wall St clings to gains as investors assess US-Iran negotiations, threats

* Indexes up: Dow 0.03%, S&P 500 0.09%, Nasdaq 0.14%

* March job gains surpass expectations, unemployment rate dips

* ISM non-manufacturing PMI decelerates, priced paid hit 3-1/2-year high

* Soleno Therapeutics (SLNO) surges on Neurocrine's $2.9 bln buyout deal (Updates to mid-afternoon)

By Stephen Culp and Purvi Agarwal

April 6 (Reuters) - Wall Street edged higher on Monday as investors looked for signs of progress toward a U.S.-Iran ceasefire deal amid President Donald Trump's progressively heated threats, should Iran fail to reopen the Strait of Hormuz.

Iran has rejected the U.S. proposal for an immediate ceasefire, insisting instead on a permanent end to the war, according to the Islamic Republic News Agency (IRNA). The rejection followed Trump's increasingly bellicose ultimatums, vowing to rain "hell" on Iran if the crucial Strait of Hormuz bottleneck remains closed to oil tanker traffic.

Investors drew some reassurance from a report that indicated the U.S., Iran and a group of regional mediators continued to discuss terms of a potential ceasefire.

All three major U.S. indexes advanced slightly, with the S&P 500 and the Nasdaq on track for the fourth consecutive day of gains.

"On a day like today investors don't do much of anything," said Thomas Martin, senior portfolio manager at GLOBALT in Atlanta. "We don't know where the truth lies with any of the stories really, whether it's on the U.S. side, the Iran side, or the Pakistan side."

Martin said, "Trump really has to get the Strait of Hormuz open ... he's made a big deal about this one," and added that investors "are all waiting on pins and needles."

The U.S.-Israeli war on Iran has roiled marketsfor a little over a month. Spiking crude prices stoked inflation fears, and stocks have tumbled. Even though the S&P was on track for its fourth consecutive session of gains, the bellwether index remains down 4% since the conflict began.

Economic data on Monday showed the U.S. services sector expanded at a slower-than-expected pace in March, even as employment contracted in the sector and prices paid, an inflation predictor, surged to its highest level since October 2022.

The much-anticipated March jobs report, released on the Good Friday market holiday, showed the U.S. economy added 178,000 jobs last month, nearly triple the 60,000 consensus, an upside surprise dampened by a revision of February's job losses, to 133,000 from 92,000.

The Dow Jones Industrial Average rose 15.40 points, or 0.03%, to 46,519.35, the S&P 500 gained 5.96 points, or 0.09%, to 6,588.65 and the Nasdaq Composite gained 31.57 points, or 0.14%, to 21,910.75.

Of the 11 major sectors in the S&P 500, communication services enjoyed the largest percentage gains, while materials were the biggest laggards.

Travel/leisure stocks and aerospace & defense were clear outperformers.

Trading volumes on Monday were expected to be thin as many markets in Europe and Asia are closed for public holidays. Shares of Soleno Therapeutics (SLNO) jumped 32.4% after Neurocrine Biosciences (NBIX) agreed to acquire the rare-disease drugmaker for $2.9 billion in cash.

Rising bitcoin prices helped U.S.-listed shares of cryptocurrency-linked firms Coinbase and Strategy advance 1.8% and 3.9%, respectively.

Advancing issues outnumbered decliners by a 1.47-to-1 ratio on the NYSE. There were 68 new highs and 41 new lows on the NYSE.

On the Nasdaq, 2,787 stocks rose and 1,843 fell as advancing issues outnumbered decliners by a 1.51-to-1 ratio.

The S&P 500 posted 7 new 52-week highs and one new low while the Nasdaq Composite recorded 50 new highs and 56 new lows.

(Reporting by Stephen Culp; Additional reporting by Purvi Agarwal and Avinash P in Bengaluru; Editing by David Gregorio)