As it turns out, the joke was on the investors. And it wasn’t a funny one. Three years later, they are embroiled in a legal battle that stretches across the European continent.

The notes were sold by Promsvyazbank (PSB), a bank founded and owned by billionaire brothers Dmitri and Alexei Ananyev. The securities promised a coupon of more than 5 per cent and carried guarantees from two companies owned by the brothers, who were well regarded in Russian society.

Later in 2017, it all went Pete Tong. After growing concerns about the bank’s stability, the Russian central bank stepped in. It first told PSB to increase its reserves and then put the bank into administration, effectively nationalising it.

The brothers fled Russia — Alexei to the UK and Dmitri to Cyprus. Russian authorities have a warrant for their arrest and have charged them with embezzlement of around $1.6bn and money laundering. Dmitri has said he is the victim of a political plot to take control of the bank. The brothers could not be reached for comment.

Caught up in this unfortunate set of circumstances are the noteholders, who are desperately trying to get their money back. Critical to their case are a rather unusual set of transactions in PSB’s shares, executed just hours before the bank was placed into administration. These transactions, some noteholders allege, were used by the brothers to extract around $1.6bn for themselves just before the central bank took over.

This task, however, is made more difficult by the spaghetti-junction structure of the brothers’ offshore companies.

They each owned a UK-based company — Antracite Investment and Urgula Platinum - which each owned just under half of a Dutch company — Promsvyaz Capital — which owned a majority stake in PSB.

A Cypriot company, Menrela Limited, jointly owned by the brothers held the remaining, tiny stake in the Dutch company. The notes, meanwhile, were guaranteed by the Dutch company and by a company in the Dutch Antilles called Peters International Investment NV, which owned a Cayman company called Peters International (Cayman) that issued the notes. (We’ve linked to the individual companies in case any of our readers want to have a rummage.)

That leaves the noteholders with the perplexing question of where to bring their court case. It also highlights how victims of alleged frauds or financial collapses can struggle to know which countries have jurisdiction in their cases, and which are simply the domicile for yet another layer in the corporate Matryoshka doll.

The first port of call for one group of noteholders was London’s High Court, chosen because it was the domicile of two of the brothers’ companies.

It was initially successful. The High Court granted a freezing order on the brothers assets - which the noteholders said included ski chalets in Megeve, France and two Bombardier Challenger corporate jets — in July 2018. The order was lifted several weeks later when Dmitri paid the frozen amount to the court. But in September last year a judge decided England was not the correct jurisdiction and ordered the money to be repaid to Dmitri.

With courts in the Dutch Antilles, the Cayman Islands and Russia all looking less enticing and/or too expensive, the group of noteholders are now trying their luck in Amsterdam. Two directors of the Dutch company — Katalin Rozsnyai and Wolfgang Ijsbrand Out — are Dutch citizens. The hope is if the noteholders can get hold of documents showing the directors acted on the orders of the brothers, they can go back to the High Court in London and ask it to reconsider the freezing order.

Ms Rozsnyai did not respond to a request for comment. Mr Out could not be reached for comment.

Meanwhile, the scandal is becoming increasingly international. A member of Germany’s Bundestag has written to authorities in Cyprus, as well as to UK Home Secretary Priti Patel and the National Crime Agency, as he says some German and US citizens are also victims. A second member of the Bundestag has written to the European Banking Authority.

The two German MPs, who call the brothers actions a “fraud”, say the “increased internationality” of frauds “leaves national legal systems unable to cope with such cases” and are calling for more international co-operation.

In an increasingly fractured world, that looks unlikely.