Vanguard Group, the Malvern based money manager has seen its worldwide institutional assets under management surge by an impressive 151% in the last five years, climbing to $2.1 trillion as of June 30. Additionally, Vanguard’s U.S. institutional tax-exempt assets under management were closing in on $1 trillion as of the same date.

In comparison, the world’s largest money manager, BlackRock Inc has only seen an increase in worldwide institutional assets under management of 34 percent for the same period, bringing its total to $3.08 trillion.

Martha King, managing director and head of Vanguard’s institutional investor group, said in a phone interview with Pensions & Investments that Vanguard’s institutional business saw the most inflows from defined contribution plans, particularly target-date funds.

“We are the largest fund manager of DC assets in the U.S. and also the No. 1 firm for target-date fund flows,” Ms. King noted.

Vanguard Group’s enviable growth led it to become the second-largest exchange-traded fund provider in early 2015, when it surpassed State Street Global Advisors, which only had $1.9 trillion in worldwide institutional assets under management as of June 30. Two years prior, Vanguard also managed to dethrone Fidelity from its position as the largest manager of U.S. defined contribution plan assets, a position that company had held since 1998.

And the good news? A lot of analysts believe Vanguard’s growth is sustainable, especially with Vanguard being very competitive on strategies, keeping costs low and offering reasonable fees. Data from Morningstar shows that the average expense ratio for Vanguard funds is 12 basis points, compared to the average expense ratio for all U.S. open-end mutual funds, which is 91. On a weighted average basis, it is eight basis points versus the industry average, which is 12 basis points giving Vanguard a competitive edge.

Daniel P. Wiener, editor of the Independent Adviser for Vanguard Investors, a newsletter with no affiliation with the company, stated that Vanguard’s growth can be seen as connected to a growing economy.

“A lot of money is 401(k) money. So, if the economy stays strong and folks continue to recognize it pays to get money into the market sooner rather than later, then yes, it’s sustainable,” said Mr. Wiener. “They’ve created a money-printing machine there with their index funds.”