* Indexes down: Dow 0.20%, S&P 500 0.03%, Nasdaq 0.21%

* Tesla, IBM ( IBM ) and Lockheed Martin ( LMT ) down after earnings

* Texas Instruments ( TXN ) gains after results

(Updates with late morning trading)

By Niket Nishant and Avinash P

April 23 (Reuters) - Wall Street's main indexes were

flat on Thursday, as investors awaited clear signals on the

U.S.-Iran war, while a batch of mixed earnings reignited

concerns about AI-driven disruption across the software sector.

Iran tightened control over the Strait of Hormuz as Tehran

released footage of its commandos storming a huge cargo ship

that they claimed to have seized on Wednesday, while demanding

the U.S. lift its naval blockade on Iranian ports.

Investors keen to look past war-related risks have shown

strong resilience in recent days, but some fatigue has set in,

leading to brief episodes of risk aversion, as they await more

clarity on how and when the conflict may ultimately be resolved.

With oil prices over $100 a barrel, the risk of an inflation

flare-up also remains.

"Our advice to investors would be not to read the

headlines," said Sameer Samana, senior global market strategist

at Wells Fargo Investment Institute.

"While there are short-term, headline-driven sell-offs time

and again, when cooler heads prevail and the market returns to

looking at fundamentals, it sees what we see, which is a really

strong economy and really strong earnings."

At 11:45 a.m. ET, the Dow Jones Industrial Average

fell 99.59 points, or 0.20%, to 49,388.60 and the Nasdaq

Composite lost 52.77 points, or 0.21%, to 24,604.80.

The S&P 500 lost 2.17 points, or 0.03%, after hitting

an all-time high.

Data on Thursday showed that the number of Americans filing

claims for unemployment benefits increased only marginally last

week, but risks from war-driven higher prices still threaten the

economy.

S&P Global's flash U.S. Composite PMI Output Index, which

tracks the manufacturing and services sectors, increased this

month after almost stagnating in March, but the improvement was

largely due to what it said was "stock building in the face of

concerns over supply availability and price hikes."

PACKED EARNINGS CALENDAR IN FOCUS

"We thought earnings would be the anchor for markets this

year, and I think thus far, the verdict is that it's the right

anchor," Samana said.

The earnings season has been largely strong so far, but

because the results reflect only one month of disruption from

the Middle East conflict, some are questioning how dependable

they are as a gauge of what lies ahead.

"The earnings themselves don't reflect the impact of the

energy supply shock," said Kiran Ganesh, multi-asset strategist

at UBS Global Wealth Management.

IBM ( IBM ) slumped 8% after revenue growth slowed in the

first quarter on weakness in its software business.

The results revived concerns that the software sector's

traditional business models could be upended by new AI tools.

The S&P 500 information technology sector fell

0.3%. Weakness in information technology stocks also sent the

Dow and the Nasdaq lower.

Tesla shares fell 2.6% after the company raised its

spending plan to more than $25 billion for the year.

Lockheed Martin ( LMT ) dropped 4.8% after reporting a lower

first-quarter profit.

Car-rental company Avis Budget's ( CAR ) shares slumped

46.3% and were on course for their steepest two-day drop ever,

after an eye-watering rally that was reminiscent of the

"meme-stock" craze.

On the flip side, Texas Instruments ( TXN ) surged 18.4%

after forecasting second-quarter revenue and profit above Wall

Street expectations.

Advancing issues outnumbered decliners by a 1.05-to-1 ratio

on the NYSE and by a 1.5-to-1 ratio on the Nasdaq.

The S&P 500 posted 36 new 52-week highs and six new lows,

while the Nasdaq Composite recorded 111 new highs and 68 new

lows.

(Reporting by Niket Nishant and Avinash P in Bengaluru; Editing

by Devika Syamnath and Shinjini Ganguli)