(Dow Jones) Vanguard Group has displaced BlackRock Inc.'s (BLK) iShares unit as the provider of exchange-traded funds with the most advisor loyalty as surveyed by Cogent Research.

Advisers' loyalty to Malvern, Pa.-based Vanguard is illustrated through overall market penetration, level of commitment and share of wallet, according to Cogent. In a news release Tuesday, Cogent said the report was released earlier this month and based on a national survey of 1,560 investment advisors.

The report used a standardized loyalty metric, known as a Net Promoter Score, which was developed by consulting firm Bain & Co. Vanguard received a score of 33% while iShares, long the leader in loyalty, received 20%, Cogent said.

"These results represent a 10-point gain for Vanguard since last year, and a corresponding eight-point drop for iShares," Cogent said.

State Street Global Advisors/SPDR ranked third overall, while Pacific Investment Management Co., which launched its first ETF in 2009, ranked fourth, Cogent said.

The average amount of assets Vanguard currently captures among the advisors it serves has more than doubled to $5.5 million per user in 2010 from $2.3 million per user in 2009, Cogent said. The $5.5 million now rivals iShares' per-advisor assets under management of $5.7 million, it said.

"Obviously, in terms of penetration, they have a long way to go to catch iShares, but, right now, the momentum is clearly with Vanguard," Cogent Principal John Meunier said in the company's statement.

BlackRock's iShares currently has $380 billion in ETF assets under management in the U.S., and $513 billion globally. Vanguard had $112.4 billion in ETF assets under management as of the end of July.

The combined assets of the nation's ETFs were $821.39 billion in July, according to the Investment Company Institute.

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