Slaughter and May has cemented its ties with longstanding client Standard Chartered Bank, advising on the issue of a $15bn (£7.45bn) debt issuance prospectus and its $860m (£427m) acquisition of American Express Bank.

Slaughters took the lead for the group company, as well as subsidiaries Standard Chartered Hong Kong and Standard Chartered First Bank Korea, the issuers on the $15bn debt programme at the beginning of the month. Slaughters' work continued as the bank agreed to acquire American Express Bank from American Express Company last week (18 September).

On both deals the Slaughters team was led by corporate partner Nilufer von Bismarck in London and Hong Kong senior partner Richard Thornhill.

The deals are the latest in a string of large mandates Slaughters has won for Standard Chartered, which also instructs firms such as Allen & Overy. In June, von Bismarck took the lead advising the bank on its $750m (£372m) preference share issue. The firm was also instructed in February advising the bank on the sale of its shareholding in Standard Chartered Trustee and Standard Chartered Asset Management to a subsidiary of UBS for $120m (£60m).

On the debt issuance, Linklaters capital markets partner Jane Brown advised JP Morgan Cazenove and Standard Chartered Bank as joint arrangers on the programme. Singapore law advice was provided by Allen & Gledhill, while Republic of Korea advice was given by Kim & Chang and US advice by Sullivan & Cromwell.

Under the programme, Standard Chartered Bank and Standard Chartered Bank Hong Kong are permitted to issue notes to be traded on the London Stock Exchange and the Hong Kong Stock Exchange. Standard Chartered First Bank Korea may issue notes on the Singapore Stock Exchange.

On the American Express deal, Slaughters worked alongside Sullivan & Cromwell M&A partner Mark Menting in the US. Skadden Arps Slate Meagher & Flom represented American Express led by corporate partners Martha McGarry and David Ingles.