Aug 15 (Reuters) - Shares of Applied Materials ( AMAT )

tumbled nearly 14% in premarket trading on Friday after the chip

equipment maker issued weak fourth-quarter forecasts on sluggish

China demand, fueling concerns over tariff-related risks.

The Santa-Clara, California-based company's forecast comes

after similar tariff warnings from ASML Holding, the

world's biggest supplier of chip-making equipment, last month.

CEO Gary Dickerson flagged lower visibility and increased

uncertainty in the near-term, citing "wide-ranging implications

for the semiconductor industry" from the dynamic policy

environment, during a post-earnings investor call.

China, Applied Materials' ( AMAT ) top revenue source in the July

quarter, accounting for 35% of sales, has emerged as a growing

risk as U.S. export restrictions weigh on new orders for

chipmaking tool suppliers.

"China volatility is significantly clouding visibility into

core earnings potential both geopolitically and cyclically,"

Deutsche Bank strategists said in a note.

Applied Materials ( AMAT ) expects revenue of $6.70 billion, plus or

minus $500 million, for the fourth quarter, compared with

analysts' average estimate of $7.33 billion, according to data

compiled by LSEG. Its projected profit also came in below

estimates.

Some analysts, including J.P.Morgan's Harlan Sur, noted that

the slowdown in China demand and erratic orders from major

foundry customers are "more a reflection of timing of spending

rather than structural issues."

The stock has risen 15.7% so far this year, compared with a

12.5% increase in the Nasdaq index and a nearly 10% gain

in the S&P 500 index.

The company's third-quarter revenue rose 8% to $7.30 billion

from a year ago, beating estimates of $7.22 billion.