FTSE 100 ends slightly higher as investors watch US tariff talks, WPP slumps

(Reuters) -The UK's FTSE 100 closed slightly higher on Wednesday, as investors monitored developments around U.S. tariff talks, while ad firm WPP slumped after it slashed its profit forecast.

WPP's stock fell about 19%, its biggest single-day percentage drop in more than three decades, as the company cut guidance after some big clients left, others cut spending and new business dried up in June.

The stock weighed on the blue-chip FTSE 100, which closed up just 0.2%.

U.S. President Donald Trump escalated worries of an expanding trade war after he threatened on Tuesday to impose a 50% tariff on imported copper and soon introduce long-threatened levies on semiconductors and pharmaceuticals.

Copper prices at the London Metal Exchange fell, as those in the U.S. traded at a premium, reflecting concerns that elevated prices across the Atlantic could suppress demand.

The UK's industrial metal mining stocks declined 1.9%, with Glencore down 2.7% and Anglo American sliding 2.5%.

The Bank of England in its half-yearly assessment of threats to financial stability said risks to financial markets remain high despite an easing of tensions after the U.S. paused implementing tariffs announced in April.

Domestic markets briefly came under pressure last week after the government had to scale back plans to cut welfare payments in the face of parliamentary opposition and doubts briefly swirled about the future of finance minister Rachel Reeves.

While markets have recovered since, concerns about global trade weighed on sentiment.

The domestically-oriented FTSE 250 index dipped 0.1%, with commercial vehicle rental provider ZIGUP slumping 9.4% on lower annual profit.

Close Brothers fell 4.2% as the lender announced its plan to streamline its premium finance business in a bid to save costs.

Among blue chips, British American Tobacco gained 2% after Jefferies assumed coverage on global tobacco with a bullish view and called the company its top pick.

(Reporting by Twesha Dikshit and Ankita Yadav; Editing by Tasim Zahid, Alexandra Hudson)