Geneva's Bank Pictet broke with a 209-year-old tradition of keeping its accounts under wraps, announcing a six-month net profit of 203 million francs ($222 million).
Operating income was 975 million francs, operating profit 247.2 million, and assets under management 404 billion francs.
Pictet said that tier one capital ratio — a measure of a bank's own top-notch funds, and a benchmark of stability — was 21.7 percent.
Under global rules, banks must have a ratio of at least 4.5 percent, while Switzerland's regulator requires 7.8 percent.
"Our financial solidity, along with the ability to set our own business strategy without pressure from external shareholders or creditors, go hand in hand with independence of mind, exacting risk management and freedom from the temptations of short term fashion," said Pictet senior managing partner Jacques de Saussure in a statement.
Pictet's results release will be followed on Thursday by Lombard Odier, while Mirabaud and LaRoche are also poised to issue their results.
"All the figures published will be important, even if these banks are not listed," Andreas Venditti, an analyst at Zurich's Vontobel Bank, told AFP.
The revolution in the secretive world of private banking — which caters for the globe's super-wealthy — began in January when Pictet and Lombard Odier ditched their two-century-old statutes.
Previously, their handful of wealthy managing partners were personally responsible for their clients' money.
In other words, if the bank got into trouble, the partners could lose all their assets, not just those they had invested in the operation.
But the increasingly complex nature of global finance made it hard for private bankers to feel safe with a traditional approach that put all their assets on the line as they expanded their operations.
The tougher regulatory environment seen since the global financial crisis, and scandals such as the Madoff fraud case in the United States which rippled across the world's banking sector, were also wake-up calls.
Switzerland's cherished tradition of banking secrecy has meanwhile been battered as governments — notably the United States and European Union — crack down on tax cheats who stash cash abroad.
As a result, the four private banks shifted from their near-unique status and transformed themselves into businesses almost like any other.
They have recast themselves a "corporate partnership", a hybrid status that makes it easier to compare them with fully-listed players such as Credit Suisse and UBS.
It is similar to the "limited company" structure in the British Isles, with its well-known "Ltd." label.
The partners now only risk the funds they have invested in the bank, rather than putting all their personal assets on the line.
Not being listed on the stock exchange, private banks do not have to publish as detailed results as mainstream banks.
For Luc Thevenoz, a law professor at the University of Geneva, the changed business model offers greater protection.
"But the price of that is more transparency," he said.
Seven lower-profile private banks have opted to stick to their traditional operating model, however.
To see Pictet's new financial report, click here.