Mark Walter's rise from an Iowa farm to owning the Los Angeles Dodgers began in the niche commercial paper market. He cut his teeth at Liberty Hampshire, mastering the art of matching assets and liabilities. In 1999, he co-founded Guggenheim Partners, which grew to manage over $300bn. Walter's breakthrough came during the 2008 crisis when he steered Guggenheim into insurance, acquiring Kansas and Delaware insurers at bargain prices. He then channelled policyholder liabilities into illiquid assets like sports and media rights — a strategy soon copied by Apollo, KKR and Brookfield.

Now that model faces intense scrutiny. US prosecutors are investigating whether insurers under Walter's TWG umbrella lent to other parts of his empire without disclosing links. In June, two TWG insurers revealed they had failed to identify more than $20bn in related-party assets. They are restructuring or selling investments to avoid ratings downgrades. A TWG Global spokesperson said the firms have created tremendous value within highly regulated industries.

Separately, Barclays hired Bank of America's Mike Joo as co-chief executive of its investment bank, aiming to simplify a leadership structure that had become too diffuse. The British lender ranks sixth globally for investment banking fees this year, trailing US rivals.