Oil major BP and Norway’s Aker said on Thursday (11 November) they have jointly sold a 5% stake in Norwegian oil firm Aker BP, cutting their combined holding in the company to 65%.

The 18.01 million shares were sold at 310 crowns each, a 10.2% discount to Wednesday’s close, for a total of 5.58 billion Norwegian crowns (US$655 million), Aker and BP said.

Aker BP was formed in 2016 through the combination of Aker and BP’s Norwegian oil and gas producing units, and the company’s shares have since risen fourfold.

The two owners said they had sought to realize some of those gains and diversify their holdings while still remaining committed to Aker BP.

“Consistent with our long-standing track-record of active portfolio management, these divestment proceeds will be expected to further strengthen (BP’s) balance sheet and support our ongoing buyback commitment,” BP Chief Executive Bernard Looney said in a statement.

As part of the transaction, Aker and BP agreed to not sell any further shares in the venture for the next six months.

“Aker BP is, and will remain, a core holding in Aker’s portfolio,” Aker Chief Executive Oeyvind Eriksen said.

“The aim of the offering is however to balance Aker’s portfolio by freeing up liquidity, diversifying and continue growing the portfolio,” he said.

Aker sold 10.29 million shares, leaving it with a 37.14% stake, while BP sold 7.72 million shares and now owns 27.85% of Aker BP.

Managers of the share sale were J.P. Morgan, Pareto Securities, DNB Markets, Goldman Sachs and Morgan Stanley.