Tobin, formerly head of iShares International, had been at the bank since 2012 and had previously worked closely with ex-private bank head David Semaya on Barclays' asset management proposition.
His departure follows that of UK wealth management head Henry Fischel-Bock in early July to join Lombard Odier, while chief executive Peter Horrell announced he will stand down at the end of the year.
Commenting on Tobin's departure, Ashok Vaswani, head of personal and corporate banking, said: 'Rory Tobin, head of Global Investments and Solutions (GI&S) at Barclays’ Wealth and Investment Management business has decided to step down from Barclays and return to institutional asset management. A search for his successor, with a proven track record, to lead GI&S is underway.'
He added that GI&S remains a core component within Barclays Personal and Corporate Banking.