Standard Life Investments is on course to become a global force in fund management, chief executive Keith Skeoch has said, after revealing that the investment arm spun off in 1998 now manages more money for external clients than for Standard Life.

"SLI will be 15 years old this year, and to see this milestone being reached in such a relatively short space of time is quite important to us," said Mr Skeoch, who earned £2 million last year and was Standard Life's highest-earning director in 2009. He joined SLI as investment chief in 1999 and became chief executive five years later.

Launched with £6bn of external assets, or just 10% of its funds, SLI last year hiked third party assets by 16% to £83 billion, just under half its total assets under management, which were up 8% at £167.7bn.

In January, rising markets pushed third party assets past 50% of the total.

Of the net inflows into SLI funds last year, 62% came from outside the UK, including £1.8bn from the US.

Mr Skeoch said: "It is incredibly important, in a world where trust in financial services is pretty low and markets are difficult, that clients are voting with their feet."

He said the performance reflected the "ongoing trust that clients have placed in Standard Life Investments' ability to provide investment solutions, strong performance, and high levels of client service".

SLI's earnings before interest and tax rose by 15% to £145m, and third party sales overseas were up 42% to £6.1bn, with 44% of sales generated from strategic partners including John Hancock (US), HDFC Asset Management (India), and Sumitomo Mitsui Trust Bank (Japan), as well as Standard Life itself.

Mr Skeoch said: "We have got good strong momentum here and that will allow us to continue on our journey of growing, which I hope will, in five to 10 years, see us as a significant force in global markets."

SLI's biggest recent success has been its Global Absolute Return Strategies (GARS) fund, launched in May 2008 and already at £21bn. Mr Skeoch said the group had "white-labelled" a similar fund for Boston-based Hancock, which had won the Wall Street Journal prize for "Rookie Fund of the Year" in 2012.

Notably, two of the group's funds, the £535m UK Equity Unconstrained, managed by Ed Legget, and the £38m UK Equity Recovery, managed by David Cumming, both achieved top three rankings out of 2883 open-ended investment funds available in the UK last year.

SLI said 91% of funds had outperformed their benchmark over one year and 81% over three years, while 34 out of 44 eligible actively managed funds were rated "silver" or above by Standard & Poor's.

Mr Skeoch said GARS and the My Folio risk-rated funds (launched last year and already up to £2bn) had been part of an innovation pipeline going back 10 years. He said: "We have got a lot of good things in the pipeline which will emerge over the next couple of years and be there to meet changing client demands."

Mr Skeoch said consultants' predictions were for global asset growth of only 1% looking forward, which meant a challenging low growth environment. "What we are consistently trying to do with our innovation platform is work out where we think markets will be in five years' time and how that will impact the client – and take the long-term view."