According to the news service’s sources, Josef Ackermann, Deutsche’s chief executive, had planned to initially take a stake of between 30 to 50 per cent, and then proceed to a majority holding in time. But it now seems that a controlling stake – which would allow Deutsche to exert greater control over the stricken wealth manager in terms of strategy – is an option.

Deutsche first announced that it was in talks to form a “strategic partnership” with Sal Oppenheim in early August, but neither the size of any possible stake nor the terms of Deutsche’s “non-binding” offer were disclosed.

A week later Sal Oppenheim said it had raised its equity capital by €300 million ($437 million) to €2.1 billion through a cash injection financed by Deutsche. At that time, a Deutsche Bank spokesperson told this publication that the funds were only credit and did not mean that any shares in Sal Oppenheim had been acquired.

Speculation over the two banks’ partnership was heightened earlier this week after Handelsblatt, the German business daily, reported on Monday that Deutsche Bank had in fact provided Sal Oppenheim with some €650 million.

However, a source familiar with the matter suggested to WealthBriefing that the “new” loan might not be such a new development at all, but rather one that had only just made its way into the public domain. The deal may have been agreed upon for some time, the source said, indicating that negotiations between the two firms may not have changed as much as some have thought.

Deutsche completed its due diligence checks on Sal Oppenheim earlier this month, and talks on the strategic partnership are expected to conclude mid-October.

Neither bank had responded to this publication's enquiries on the matter at the time of publication.

One of Europe’s oldest private banks, Sal Oppenheim suffered a net loss of €117 million in 2008. The firm has been looking to sell its German BHF banking unit, but has reportedly said it is in no hurry to offload this business.