Credit Suisse is promoting veteran Swiss investment banker Thomas Gottstein to head up its ultra-rich clients business in Switzerland, highlighting the expertise increasingly sought by private banks to cater to their wealthiest customers.

Both Credit Suisse and crosstown rival UBS are trying to sell their capital markets expertise through their wealth management divisions, ramping up sophisticated and tailor-made products and services in a bid to win more business from clients with more than $50 million in bankable assets.

Gottstein, currently head of relationships with Credit Suisse's Swiss investment banking clients, will replace Rolf Boegli as head of ultra-high net worth customers in Switzerland from Jan 1, according to a memo seen by Reuters on Friday.

Credit Suisse is aiming to increase the contribution of ultra-rich clients to its overall assets under management to around half from 44 percent now, in part by using its large balance sheet to lend more to wealthy individuals. 

The focus on the ultra-rich marks a shift from chasing the "mass-affluent", or moderately rich.

While investment banking suffers from volatile post-crisis markets and curbs on risk-taking, private banking is growing, with households worth more than $100 million expected to account for $11.6 trillion of global private wealth by 2017, up from $7.5 trillion last year, according to Boston Consulting Group.

Boegli, who is stepping down at the end of the year for health reasons, had been in his current job for little more than a year following the merger of the bank's retail and private banking arms in Switzerland.

He is taking a leave of absence and plans to return to Credit Suisse eventually, according to the memo, whose contents were confirmed by the bank. The job overseeing ultra-rich clients also includes oversight of third-party asset managers.