ZURICH, (Reuters) – Klaus-Michael Kuehne is increasing his stake at German flag carrier Lufthansa by 10%. Kuehne Holding AG made this announcement Monday.

Kuehne (84) had increased his Lufthansa share to 5% less than a month before, and became the second largest shareholder of the airline behind the German government. Refinitiv data shows that Kuehne was the most successful investor in Lufthansa.

Kuehne Holding AG purchased a 10% stake in Deutsche Lufthansa AG (OTC:), on the German market through a subsidiary wholly owned by Klaus-Michael Kuehne.

Kuehne said in the statement, “The Deutsche Lufthansa (DE) investment represents an excellent rounding out of the existing portfolio. In which logistical expertise is bundled via various independent holdings,”

The German billionaire is also the controlling shareholder of Swiss logistics firm Kuehne & Nagel and has a 30% stake in container shipping company Hapag-Lloyd AG.

Lufthansa reported last week that it signed a 2.0 billion euro ($2.18 billion), revolving credit facility with an international syndicate of relationship banks in order to improve its liquidity.

($1 = 0.9189 euros)