National Australia Bank (NAB) is set to sell its remaining 28.5% stake in the regional US lender Great Western Bancorp.

The move is part of NAB CEO Andrew Thorburn’s plan to exit its underperforming operations in order to refocus on its core franchises in Australia and New Zealand.

Great Western has now filed a registration statement with the Securities and Exchange Commission (SEC) for a possible secondary listing of shares owned by its Australian parent, though it did now specify how much it expected the shares to sell for.

Last year, NAB offloaded a 31.8% stake in Great Western at $18 per share in an IPO that raised $331m. In May, it moved to raise $495m by selling shares at $21.50 each, to dilute its holding to 28.5%.