Helena Helmersson said she was leaving the firm after four years and did not have the energy to continue.

Company veteran Daniel Ervér took over with immediate effect.

Shares in the Swedish fashion retailer dropped over 10% on the update.

The leadership change comes while the firm struggles to boost sales and profitability.

H&M said sales for December and January fell by 4% compared to the previous year.

That was a bad sign for the key Christmas shopping period.

Fourth-quarter operating profit reached $415.4 million - it was up from a year ago, but below analyst projections.

H&M has struggled to compete with Inditex-owned Zara and fast fashion giant Shein.

Both rivals have seen strong sales growth.

H&M has focused on profitability rather than sales volumes recently as it aims to reach a 10% operating margin this year.

New boss Ervér is 42 and has been at H&M for 18 years - most recently as head of the retailer's core H&M brand.