The iconic British luxury brand Burberry (LSE:BRBY) has begun preparing for a takeover battle after finding itself in the crosshairs of an unknown investor.

The $8.5 billion designer brand recently disclosed that an outside party had briefly accrued a 5 percent stake in the company in February, triggering a mandatory reporting requirement. The investor’s custodian, British bank HSBC, has yet to reveal to Burberry who the interested party is, the Financial Times reported Tuesday.

Burberry has retained the counsel of boutique London investment bank Robey Warshaw, in addition to Morgan Stanley, in an apparent attempt to rebuff the outside interest. Shares in Burberry rose more than 6 percent Tuesday in London trading.

Burberry sales have languished in the past year as demand from China has cooled, sending shares down nearly one-quarter since a 2014 peak, from $27.13 to $20.73 today. That decline, combined with Burberry’s lack of family control, Macquarie analyst Daniele Gianera told the FT, make the company “an easier target” for takeover.

Founded in 1856, the London company is known for its distinctive trenchcoats in a signature beige/black/white plaid motif. Burberry operates more than 500 stores in 50 countries.