LONDON (Reuters Breakingviews) - In recent years, the mere mention of Deutsche Bank’s wholesale business has been enough to elicit a titter from rival bosses. They assumed that Chief Executive Christian Sewing’s 2019 decision to shrink the unit and scrap businesses like equities trading would prompt a client exodus. It hasn’t worked out that way. Sewing revealed on Thursday that Deutsche’s investment banking division generated 1.9 billion euros of revenue in the fourth quarter of 2020. That was 24% higher than a year earlier, more than double the year-on-year increase reported by American rivals including JPMorgan and Goldman Sachs. Deutsche’s fixed-income and currency trading operations now account for about three-quarters of the unit’s income, with debt underwriting bringing in almost a fifth. Fees from equity offerings and advising on mergers contributed a token amount. Meanwhile costs for the full year, excluding restructuring and legal charges, were about one-tenth lower than in 2019. The slimmed-down franchise is holding its own. In the second half of 2020, Deutsche’s revenue from trading bonds and currencies was 14% of the combined total of the big five American banks, using average quarterly euro-dollar exchange rates. That’s almost exactly the same proportion as in the first six months of 2019, just before Sewing started wielding his machete. Deutsche’s average quarterly share of global debt underwriting fees rose slightly to 3.5% in 2020, according to Dealogic. It’s too early to declare Sewing’s restructuring a success, though. The bank finally climbed out of the red in 2020, but a target for a group-wide 8% return on tangible equity for 2022 still looks hopeless: analysts on average expect less than half that. And investors are apt to feel nervous about the risks building up in the investment bank given Deutsche’s chronic history of control failures. Risk-weighted assets in the unit are now 10% higher than at the end of 2019. Wholesale revenues will probably decline if market volatility ebbs in 2021. Yet Deutsche’s surprising resilience nonetheless proves an important point. As with UBS’ 2012 decision to nix its fixed-income trading business, the German group has shown that it’s possible to lop a whole limb off an investment bank without fatally wounding what remains. HSBC, and Credit Suisse, which both have relatively new CEOs with a mandate to shake things up, ought to be watching closely.