So much for the post-crisis idea that the UK’s big four banks would be knocked off their comfortable perches by a combination of new technology and “challenger” banks. A decade on, it’s hard to detect a meaningful shift in market shares. Lloyds Banking Group, the undisputed leader in the UK, isn’t noticeably weaker for being shorn of TSB and last year got bigger in credit cards, the only corner in which it was underweight, by buying MBNA’s operation in the UK.

It’s little wonder, then, that challengers are concluding they won’t get far on their own. CYBG, which isn’t a true new-breed challenger anyway since Clydesdale Bank was born in Glasgow in 1838 and Yorkshire Bank in Halifax in 1859, wants to merge with Virgin Money to “create the UK’s leading challenger bank” to offer “a genuine alternative to the large incumbent banks”.

Top marks for hype but the proposal looks more defensive than aggressive. The idea is to create a full-service bank, which both parties would struggle to do quickly under their own steam. CYBG is stronger in small business banking and current accounts, whereas Virgin is focused on mortgages, savings and credit cards. So, yes, there is commercial logic here. If Virgin is keen, it may be able to push CYBG to improve its terms.

Just don’t expect the banking landscape to quake. With 6 million customers, the new entity would overtake TSB but would still be miles behind banking’s second tier, which comprises Santander UK and Nationwide Building Society. Indeed, compare deal sizes. Virgin Money is valued at £1.6bn on CYBG’s proposal but Lloyds’ paid £1.9bn for its MBNA purchase and could call the deal a fill-in. The difference in scale is enormous.

One of these decades, the financial technology, or fintech, revolution may change the rules of engagement. But for the time being, the benefits of size remain enormous for the bigger beasts, and were reinforced by the Competition and Markets Authority’s timid report into the sector in 2015. A merger between CYBG and Virgin would be sensible for both banks – but it would also confirm that politicians were selling a false prospectus when they said “challenger” banks would change everything.

Shire takeover: debt-heavy and overambitious

For most bidding companies, a 18% fall in their own share price during takeover negotiations would kill the adventure stone dead. That is especially so when the bid is high-risk, cross-border and involves raising monumental sums of debt. Takeda Pharmaceutical of Japan, though, is undeterred. It has spent six weeks tying to get the board of the FTSE 100 firm Shire to agree terms and has finally got a thumbs-up for a cash-and-shares offer at £46bn, or a shade over £49 a share.

The fact of a recommendation was enough to give Takeda’s shares a small bounce for almost the first time since this saga started in March. Yet, for those looking in from the outside, this proposed deal – which is really a reverse takeover since Takeda is the smaller company – screams of over-aggressive financing.

Takeda is taking on a cool $31bn (£22bn) of bridging finance and the new combination would start life with debt equivalent to between four and five times its top-line operating profits. A maximum of two times is generally deemed prudent in an industry such as pharmaceuticals where drugs can fail in clinical trials despite hefty investment.

Don’t worry, says the Takeda chief executive, Christophe Weber, a former GlaxoSmithKline executive, the ratio will fall to two times within “three to five years” because the cashflows are strong and because annual cost savings of $1.4bn can be found. Well, yes, if everything runs perfectly, the financial arithmetic can be made to work. But take a step back: Takeda is offering a mighty 64% premium to Shire’s share price in mid-March. That’s one hell of a punt to take to join the pharmaceutical big league.

Weber has convinced Shire’s board, which was his first battle. But gaining support from shareholders will not be straightforward. Both sets of investors have reasons to worry: this deal looks ambitious in the sense of being top-of-the-market and a lot can happen before the intended completion next year.

Smaller is beautiful, says Martin Sorrell

Sir Martin Sorrell didn’t explain his departure from WPP – no surprise there – but he did tell a conference in New York on Tuesday that he wanted to “start again” in the advertising business. He also has an idea for what a 21st-century agency should look like: “More agile, more responsive, less layered, less bureaucratic, less heavy.” One assumes those comparisons are with WPP itself. If so, why didn’t he change the model when he had the chance?