New York-listed Diamond S Shipping has filled out its complement of directors who will join the board of an enlarged International Seaways once an all-cash merger is completed later this year.

Private equity executive Nadim Qureshi and independent director Alexandra Kate Blankenship – a long-time fixture in the John Fredriksen group – are slated to land on the Seaways board, where they will join current Diamond S chief executive Craig H Stevenson Jr.

Connecticut-based Diamond S is allowed three seats on the new International Seaways board under terms of a merger agreement announced earlier this year. International Seaways will control seven seats, and its management team will control the combined company.

International Seaways' shareholders will own 55.75% of the new company, with Diamond S investors having 44.25% after receiving stock worth $416m.

Qureshi had chaired the Diamond S board as a representative of Invesco, which is Diamond's largest shareholder through its WL Ross & Co unit.

WL Ross was founded by legendary investor Wilbur L Ross, who later became US commerce secretary. According to latest filings, WL Ross continues to own roughly 8.9m shares in Diamond, or about 22% of the tanker owner.

Qureshi departed Invesco last year and co-founded BroadPeak Global, an independent private equity firm involved in "opportunistic buyouts". However, sources have suggested that he maintains close ties with Invesco, as his continued presence on the board implies.

From the Diamond perspective, one rationale for the acquisition is that it creates a larger combined company with an enterprise value approaching $2bn and an expected market capitalisation around $1bn, providing greater trading liquidity for an investor like WL Ross to cash out.

Blankenship is an independent director with more than 20 years of shipping experience. She is a former executive of Fedriksen's trademark tanker company Frontline, and has served as a director of such group companies as Golden Ocean Group, Avance Gas and Ship Finance International.

Four current Diamond S directors will not make the transition over to the new board. They include Jerry Kalogiratos, executive of shareholder Capital Maritime; veteran finance executive Hal Malone, another Invesco alumnus who now heads advisory firm White Fir Global; long-time ship lender Bart Veldhuizen; and accounting specialist George Cambanis.

The combined International Seaways fleet will number 100 ships of 11.31m dwt, with revenue of more than $1bn.

Stevenson is to continue for six months as a special advisor to International Seaways chief executive Lois Zabrocky to ensure a smooth transition.