Revived Japanese banks are a constant force. Just as two uninspiring lenders – both failed banks that were nationalised and then sold to private equity firms – plot to join and become one, a third is being readied for market. Shinsei Bank, backed by a group of investors including Christopher Flowers, and Aozora Bank, backed by Cerberus, on Thursday confirmed they were in merger talks. Meanwhile, Nomura, which led a consortium to buy Ashikaga Holdings, unveiled plans to list that failed regional lender.

Investors whooped, driving the share prices of Aozora and Shinsei up 11 per cent equally. This common treatment is apposite as the deal is destined to be a taito gappei, or merger of equals, in keeping with Japanese tradition. Although Shinsei has a bigger market capitalisation, after that the two stack up evenly: both trade at about 0.6 times book and deliver negative returns on equity. Justifying the size of the share price rise is harder, though, as the merits of the merger look broadly superficial.