Deutsche Lufthansa AG’s second-largest shareholder is selling more than half its stake in the airline group three months after the death of family patriarch Heinz Hermann Thiele.

KB Holding GmbH, through which Thiele built an around 12% stake in the German company, will sell 33 million of its 60 million shares, according to a statement late Thursday. At current prices, the part being disposed is valued at about 358 million euros ($437 million).

The timing means Thiele’s heirs will be selling at prices about one-third below where Lufthansa traded before the coronavirus crisis slammed the airline industry. Europe’s largest carrier required a 9 billion-euro bailout to survive, while cutting back on its fleet and staffing. The company recently gained investor approval to raise up to 5.5 billion euros in capital to pay down some of the debt it took on.

The Thiele family is the largest private shareholder in Lufthansa, after the German government, which obtained a 20% holding with the bailout last year. The family had previously cut its stake to 10.1%, according to regulatory filings.

Thiele, who was 79 when he died in February, took center stage last year as an activist investor in a drama gripping Lufthansa. After building his stake, he expressed dissatisfaction with the German government’s rescue plan, before ultimately supporting it.

His family may owe German authorities more than 5 billion euros in inheritance taxes, potentially the largest such bill in the country’s history, according to ManagerMagazin. Thiele’s assets were meant to be placed in a foundation to reduce tax risks, but it wasn’t set up when he died, the magazine reported in April.

Read more: Heirs to German Industrial Fortune Face $6 Billion Tax Bill

Thiele built an empire spanning real estate, industrials and agriculture after starting his career in 1969 at Knorr-Bremse AG, the brake-system manufacturer he turned into a global leader.

Lufthansa shares closed little changed Thursday at 10.87 euros in Frankfurt. The company has a market value of 6.5 billion euros.