Total assets under management ( AuM ) of the world's largest 500 managers grew to US$93.8 trillion in 2017, representing a rise of 15.6% on the previous year, according to the latest Global 500 research from Willis Towers Watson's Thinking Ahead Institute. In addition, the concentration of assets managed by the 20 largest managers reached the highest level since inception ( in 2000 ), and now account for over 43% of the top 500 managers' total AuM.

The research, which takes into account data up to the end of 2017, shows that AuM for Asia Pacific managers in the global ranking totaled US$8.1 trillion, up 17% on the year. The increases in AuM for managers in Europe ( including the UK ) and North America were 15.8% and 15.1% respectively.

The growth in assets managed by managers in Asia Pacific exceeded the growth rate of Europe, North America and the broader group of 500 firms.

Jayne Bok, head of investments at Asia Pacific, says: "Asia ex Japan equities experienced the best performance over 2017. The strong equity returns helped boosting the growth in managers' AuM with a higher exposure to Asia. Investors should consider diversifying sources of return in constructing a portfolio that can withstand a wide range of economic environments."

Within Asia Pacific, Japan at US$4.5 trillion represents the largest share of the assets managed by managers domiciled in Asia Pacific, followed by Australia with US$1.3 trillion. Assets managed by mainland Chinese managers amounted to approximately US$1.1 trillion in 2017, which would rise to US$1.2 trillion if the AuM of four Hong Kong managers ( US$135 billion ) is included. There is a new entrant from Malaysia.

The research shows North America-based managers represent the majority of assets ( 58.1% ), although their share fell slightly in 2017, the first fall since 2008. European managers represent 31.8% of assets managed ( the UK being 7.4% ), Japan 4.8% and the rest of the world 5.2%. Assets in each region grew in 2017. While the majority of total assets ( 77.6% ) are still managed actively, the share of passive assets has grown from 19.5% to 22.4% in the last five years. In 2017 passive assets grew 25%.

BlackRock remains the largest asset manager in the rankings, a position it has held since 2008 and Vanguard and State Street complete the top three for the fourth successive year.

Bok notes: "Once again, total assets have increased and the rate of growth in 2017 is the biggest since 2009. The names at the top of the ranking are familiar names. There is greater concentration in the biggest names. On the surface, the numbers might appear to tell a story of steady growth and of stability. But when you look at broader developments within and beyond the industry, there are signs that the industry is facing significant change."

According to the research, more than four out of five ( 81% ) of managers surveyed reported an increase in client interest in sustainable investing, including voting, while nearly three quarters ( 74% ) increased resources deployed to deal with technology and big data.

Bok adds: "There is a confluence of global megatrends – including technological, demographic, economic, environmental and social pressures – that are combining to create a period of potentially massive disruption for the industry. These trends have implications for every aspect of the asset manager's structure. Successfully responding to these realties may prove to be as much a test of character and culture as it is a test of traditional business and investment skills. Culture can be difficult to preserve as a firm grows, but it is crucial as the bedrock on which a competitive advantage is sustained over the long term."