A looming price war in the "smart beta" ETF space represents a negative for active asset managers, says a report published Thursday from Moody's Investor Services.

The report notes that earlier this week, Goldman Sachs Asset Management announced it plans to launch a new smart beta ETF that will charge a management fee of just nine basis points (bps) — well below the fees charged by most funds in the sector. Most smart beta ETFs currently charge between 24 and 39 bps, according to the report.

The move to launch a low-cost rival, "expands the ETF price war beyond plain vanilla ETFs into smart beta ETFs, implying that the industry's higher pricing assumptions for smart beta products will not hold," the Moody's report says.

This will be negative for both existing players in the smart beta segment and traditional active managers that may enter the space, the report says. Many traditional active managers are looking to smart-beta products as a category where, "they could grow assets without too much sacrifice on revenue," the report adds.

"Smart beta products will continue to grow and attract assets at a fast pace. However, it may now be that the vast majority of smart beta products may not be able to command a meaningful premium over vanilla index products," the report says.

"As a result, much of the hope and investment traditional managers placed into smart beta as a product salvation may be at risk. This is negative for traditional active managers that move into this space and expect to charge active light management fees, but will rather face a more index-like pricing environment," the report concludes.