(Updates with closing prices)

March 28 (Reuters) - Japan's Nikkei average ended at a

two-week low on Friday in a broad selloff, with automakers

leading the losses, as concerns over the potential impact of

U.S. President Donald Trump's trade tariffs weighed.

The Nikkei lost 680 points, or 1.8%, to close at

37,120.33, its lowest close since March 14.

A majority of stocks going ex-dividend resulted in a loss of

around 300 points, strategists said.

The broader Topix slipped 2.07% to 2,757.25.

"Uncertainties about the impact of the U.S. tariff plans

weighed on sentiment," said Naoki Fujiwara, senior fund manager

at Shinkin Asset Management.

Automakers Toyota Motor ( TM ) slumped 4.53%, while Honda

Motor ( HMC ) dropped 4.88%. Almost three trillion yen ($20

billion) has been wiped from the market value of Japan's top

three carmakers - Toyota ( TM ), Honda ( HMC ) and Nissan ( NSANF ) - in three

trading sessions through Friday.

Earlier this week, Trump declared his plan to implement a

25% tariff on imported cars and light trucks, effective from

April 3, while the duty on auto parts begins on May 3.

Investors also braced for a wave of reciprocal tariffs that

Trump plans to unveil on Wednesday, although he has hinted there

may be room for flexibility.

All of the Tokyo Stock Exchange's 33 industry sub-indexes

fell, with the brokerage sector falling 4.52% to be

the worst performer. The transport index lost 4%.

"Even value shares, which had been supporting local

equities, fell today because investors had secured dividend

payouts by Thursday," said Fujiwara.

Thursday was the last day for investors to secure rights to

dividend payouts for companies with a fiscal year ending in

March. Investors scooped up value shares, which pay higher

dividends than growth stocks.

Banking shares declined, with Mitsubishi UFJ Financial Group ( MUFG )

and Mizuho Financial Group ( MFG ) and Sumitomo Mitsui

Financial Group ( SMFG ) slipping 3.21%, 3.96% and 3.24%,

respectively.