Citigroup has won its fourth corporate broking mandate in a month after being appointed joint broker to UK platinum mining company, Lonmin, where it will work alongside JP Morgan Cazenove.

The mandate, which follows roles working for UK insurer Brit Insurance, Hikma Pharmaceuticals and Pendragon, the UK car retailer, means that Citigroup has increased its roster of corporate broking clients by more than half in the seven months since Nigel Mills joined as chairman of the business in September.