What is the link between the following political scandals? The Petrobras case in Brazil, the 1MDB affair in Malaysia, the unravelling of Fifa, the prosecution of a French minister and a party funding row in Spain.
The answer is Swiss bank accounts.
Customers used to be able to rely on the legendary discretion of the "gnomes of Zurich" but Swiss bank accounts are no longer as secret as many clients once assumed. These days, if prosecutors in another country ask the Swiss for cooperation in a corruption investigation, they will get it. As a result, powerful people who might have hidden money in Switzerland are increasingly vulnerable to investigation.
The biggest changes in Switzerland's banking culture followed the huge fines that the United States levied on UBS, a Swiss bank, in 2009, for enabling Americans to evade tax. Further US prosecutions of Swiss banks followed, as well as a tightening of American tax law. The European Union also began to increase pressure on the Swiss.
Partly as a result, Switzerland has made decisive moves away from its traditional culture of bank secrecy. The consequences are playing out worldwide.
The case of Jerome Cahuzac, the former French budget minister who went on trial for tax fraud in Paris last month, illustrates the pattern.
The biggest changes in Switzerland's banking culture followed the huge fines that the United States levied on UBS, a Swiss bank, in 2009, for enabling Americans to evade tax. Further US prosecutions of Swiss banks followed, as well as a tightening of American tax law. The EU also began to increase pressure on the Swiss.
Ironically, Cahuzac had been asked to lead a campaign against tax evasion by President Francois Hollande. In late 2012, however, he was accused in the French media of having kept his own secret bank account in Switzerland. He denied accusations vehemently for months, before resigning suddenly in April 2013. The trigger, it seems, was news that the Swiss were cooperating with French prosecutors.
The Cahuzac case illustrates the way in which past actions can catch up with Swiss banking clients. Some years before his Swiss account came to light, Cahuzac had closed it and transferred his funds to Singapore. But banks keep records, so closing an account does not always close a case.
Cahuzac is just one individual but in Brazil, large parts of the business and political elite are threatened by revelations emerging from Switzerland. A bribery scandal involving Petrobras, the national oil company, is revealing illicit payments, and much of the information is coming from Swiss prosecutors.
Last month, the Swiss arrested Fernando Migliaccio da Silva, a Brazilian businessman and former executive of the Odebrecht construction company, as he attempted to close an account in Geneva. Mr da Silva was suspected of paying bribes to Petrobras directors, through accounts in Switzerland. Marcelo Odebrecht, the billionaire former chief executive of the company, has just been jailed for 19 years for his role in the Petrobras scandal.
Other prominent Brazilians have also been caught out by their Swiss connections. Joao Santana, the former campaign manager for President Dilma Rousseff, has been arrested and accused of illegally depositing money in Swiss bank accounts. Eduardo Cunha, the Speaker of Brazil's Lower House of Parliament, faces charges of hiding millions in Petrobras-related bribes in Switzerland.
The Petrobras case shows that the Swiss authorities are prepared to take the initiative in revealing potential corruption. They have also played an important role in keeping alive a politically explosive corruption probe in Malaysia, where Prime Minister Najib Razak has always denied allegations that a payment of US$681 million (S$933 million) that made its way into his personal bank account, via a Swiss bank, had anything to do with an official Malaysian development fund, known as 1MDB. The Malaysian authorities have cleared Datuk Seri Najib and 1MDB has also denied wrongdoing.
In late January, however, allegations about corruption in Malaysia were given fresh impetus when the Swiss announced that their own investigation into 1MDB had revealed "serious indications" that US$4 billion had originated from Malaysian state concerns.
Fifa, the governing body of world football, which is already threatened by US prosecutors, also has to worry about Swiss money-laundering investigations. The Swiss are looking into transactions that might be related to bidding processes for the 2018 and 2022 World Cups.
Investigations relating to Swiss banks have also had a major effect on Spanish and Greek politics. One of the reasons that Spanish Prime Minister Mariano Rajoy failed to secure a majority in elections in December was the backwash from a scandal: in 2013, it was revealed that Luis Barcenas, the former treasurer of Mr Rajoy's People's Party, had accumulated millions of euros in Swiss bank accounts, which he had allegedly used to make illicit payments in Spain.
The financial crisis in Greece, meanwhile, has shone a spotlight on widespread tax evasion by its elite. A list of more than 2,000 Greeks with accounts at the Geneva branch of HSBC became known as the "Lagarde list", after Ms Christine Lagarde, who, when she was finance minister of France, handed it to the Greek authorities in 2010.
The Lagarde list had been stolen by a disgruntled employee. The more recent revelations to come out of Switzerland have emerged through official channels.
In 2018, Switzerland will move to automatic exchange of information with other global tax authorities. There may well be further scandals to come.
THE FINANCIAL TIMES