* Western Digital ( WDC ), Sandisk ( SNDK ) slide despite upbeat forecasts

* AppLovin ( APP ) down after Q2 revenue misses estimates

* Moderna ( MRNA ) rises after US approval for flu vaccine

* Futures: Dow up 0.23%, S&P up 0.15%, Nasdaq down 0.55%

(Updates to before markets open)

By Johann M Cherian and Shashwat Chauhan

Aug 6 (Reuters) - The S&P 500 and the Dow were set for a

steady open on Thursday, building on this week's record rally as

investors awaited details on a Middle East peace deal, while

Nasdaq futures slipped as strong forecasts from Western Digital ( WDC )

and Sandisk ( SNDK ) failed to impress.

Data storage company Western Digital ( WDC ) lost 14.4% and

memory chip maker Sandisk ( SNDK ) dropped 10.4% in premarket

trading, after having shot up 200% and 400% this year. Both

companies forecast quarterly revenue above expectations, betting

on strong AI-driven demand.

"Expectations (for Western Digital ( WDC )) got priced for outright

acceleration (not just continued strength)," said Luke Lango,

chief technology analyst at financial research firm

InvestorPlace.

"When the growth and margin trajectory came in 'merely'

excellent rather than re-accelerating, an extremely crowded,

high-momentum stock got dumped alongside the broader AI-memory

complex that's been unwinding all week."

Shares of other chip stocks such as Micron shed 4.6%,

while Advanced Micro Devices ( AMD ), Marvell Technology ( MRVL )

and Intel ( INTC ) lost over 1% each.

Software stocks were also broadly lower, with Atlassian ( TEAM )

, Salesforce ( CRM ), Adobe and Zscaler ( ZS )

all down sharply following earnings reports from a few companies

in the sector.

AppLovin ( APP ) dropped 19% as the marketing platform

missed Wall Street estimates for quarterly revenue, while cloud

security firm Datadog ( DDOG ) lost 15.6% after reporting

second-quarter results.

Megacaps such as Meta and Amazon ( AMZN ) were

marginally higher, while Alphabet dipped 0.3% after a

report said the company is looking to raise as much as $25

billion from its latest U.S. bond offering. The stock ended down

4% in the previous session on an announcement about a leadership

overhaul of its AI division. Apple ( AAPL ) rose 1%.

SpaceX rose 2.3% ahead of the space conglomerate's

first post-IPO share lockup expiry. The broader AI-linked group

of stocks showed signs of cooling from a rally.

Strong earnings from tech leaders this reporting season have

restored investor confidence that AI investments were being

monetized, which helped the benchmark S&P 500 and the

blue-chip Dow reclaim record highs earlier this week.

The Nasdaq is about 3% away from an all-time high,

bouncing off last week's lows, which saw the index coming close

to confirming a correction.

At 8:38 a.m. ET, Dow E-minis were up 125 points,

or 0.23%, and S&P 500 E-minis were up 11.5 points,

or 0.15%. Nasdaq 100 E-minis were down 161.5 points,

or 0.55%.

Brent crude prices traded in a tight range near $80

a barrel as markets were keen on any signs of a deal between

Iran and the United States. A proposed deal between Iran and

Oman would give Tehran control over ships entering the Gulf

through the Strait of Hormuz, sources told Reuters.

The Federal Reserve has been keen on the outlook for energy

costs, with most central bankers voicing that they were prepared

to act if price pressures increase. St. Louis Fed President

Alberto Musalem is expected to speak on monetary policy later in

the day.

With Fed Chairman Kevin Warsh staying mum on forward

guidance, traders are struggling to gauge the central bank's

next policy move.

Probabilities for no change versus a rate hike in September

are now closer to even, the CME FedWatch Tool showed. Last week,

traders were pricing in a 37% chance for rates staying unchanged

versus 63% for a rate increase.

A Labor Department report showed weekly jobless claims stood

at 199,000, missing economists' expectations of 202,000 heading

into the nonfarm payrolls figures for July due on Friday.

Among other stocks, Moderna ( MRNA ) rose 3.9% after the

U.S. Food and Drug Administration approved the company's flu

vaccine for people aged 50 and older.