(For a Reuters live blog on U.S., UK and European stock

markets, click or type LIVE/ in a news window)

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US job openings rise to 7.74 million in January

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Delta Air Lines ( DAL ) lowers first-quarter forecast, shares fall

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Kohl's slides on bleak annual sales forecast

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Dow Transportation index touches seven-month low

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Indexes: Dow slips 0.85%, S&P 500 off 0.37%, Nasdaq up

0.18%

(Updates to mid-session trading)

By Johann M Cherian and Pranav Kashyap

March 11 (Reuters) - The Dow and the benchmark S&P 500

fell in choppy trading on Tuesday after U.S. President Donald

Trump announced fresh tariffs on Canada, adding to investor

unease that his trade policies could trigger an economic

slowdown.

Trump doubled his planned tariffs on all imports of steel

and aluminum products from Canada to 50%, in response to the

province of Ontario's decision to place a 25% tariff on its

electricity exports to the United States.

He also threatened to "substantially increase" tariffs on

cars coming into the U.S. on April 2. Ford and General

Motors ( GM ), that have vast supply chains across North

America, fell around 3% each.

Global markets have been roiled ever since Trump sparked

back-and-forth tariff moves against major trading partners such

as Canada, Mexico and China. Analysts have warned that the

escalating trade tension could fan inflationary pressures and

potentially stall economic growth.

On Monday, the S&P 500 recorded its most significant one-day

drop since December 18, wiping out a staggering $4 trillion from

its recent peak. Meanwhile, the tech-heavy Nasdaq confirmed a

10% correction late last week.

"Every time we feel like we're getting a little bit of a

lift, we get a Trump update on more tariffs," said Dennis Dick,

a trader at Triple D Trading.

"International investors looking at all the political

uncertainty in the North American markets are saying let's

invest elsewhere."

At 11:46 a.m. ET the Dow Jones Industrial Average

fell 356.14 points, or 0.85%, to 41,555.57, the S&P 500

lost 21.02 points, or 0.37%, to 5,593.54 and the Nasdaq

Composite gained 31.77 points, or 0.18%, to 17,500.09.

Nine of the 11 S&P 500 subsectors fell, led by a 0.8% drop

in industrials. The S&P 500 equally weighted index

lost 1%.

Tariff uncertainty has also weighed on consumer sentiment,

with company executives increasingly flagging the impact it can

have on upcoming earnings.

Kohl's forecast a bigger-than-expected drop in

annual comparable sales, sending the retailer's shares down 23%.

Dick's Sporting Goods declined 5.9% after the

retailer forecast downbeat annual results.

Delta Air Lines ( DAL ) slid 7% after the carrier slashed

its first-quarter profit estimates by half.

American Airlines ( AAL ) also dropped 4.8% after the

carrier forecast a bigger-than-expected first-quarter loss,

sending the broader Dow transportation index down by

2.5%.

"(Tariff uncertainty) is creating a degree of paralysis

across the system," said David Russell, global head of market

strategy at TradeStation.

Trump will meet the chief executives of America's biggest

companies later in the day.

Meanwhile, a U.S. Labor Department report showed job

openings increased in January. A closely watched inflation

report is expected later in the week.

Interest rate futures point to the U.S. Federal Reserve

leaving borrowing costs unchanged at its meeting next week, but

traders are increasingly pricing in more interest rate cuts in

the second half of the year on expectations of slowing growth.

Aiding gains on the Nasdaq, megacaps such as Nvidia ( NVDA )

rose 3% and Amazon.com ( AMZN ) added 1.8%, while Tesla

added nearly 4.6% after the stock fell 15.4% in the previous

session.

Oracle dropped 3.7% after the cloud company missed

quarterly revenue estimates.

Citi became the latest brokerage to revise its stance on

U.S. stocks, downgrading its recommendation to "neutral".

Declining issues outnumbered advancers for a 1.43-to-1 ratio

on the NYSE and a 1.14-to-1 ratio on the Nasdaq.

The S&P 500 posted four new 52-week highs and 14 new lows,

while the Nasdaq Composite recorded 15 new highs and 267 new

lows.