Barclays (NYSE:BCS) closed out the first half of the year with a double-digit climb in pretax profit as volatile markets fueled relatively strong gains in its investment banking unit. The U.K. lender -- which also confirmed a £1B share buyback and declared a half-year dividend of 3.

Investors have been watching the performance of the lender's sharpened investment banking unit, which posted income of £3.3 billion the three months to June.

Barclays' first-half profit rose by a better-than-expected 23%, the British bank said on Tuesday, as its markets business reaped bumper returns from the frenzied trading activity sparked by U.S. President Donald Trump's trade tariffs.