AllianceBernstein (NYSE:AB) executives last week hosted a conference call to discuss the investment manager's third-quarter results. Were the numbers impressive enough to match the year-to-date total return of 42% in AllianceBernstein's partnership units?

Net income rose to $0.87 per unit, a 17.6% increase year over year. Revenue growth was largely flat on a linked-quarter basis, but showed an increase of 17.5% from the previous year. Assets under management grew from $625.2 million at the end of the previous quarter to $659.3 million, a 5.5% increase.

That increase occurred against a background of buoyant market indexes, with nearly all investing styles and asset classes posting strong returns in the third quarter, supporting the robust investment returns delivered by AllianceBernstein funds. Assets under management at AllianceBernstein also increased, as a result of $8.3 billion of net investment inflows from clients.

International investments continued to be an important product for AllianceBernstein. The firm is well-known for its international funds, and those funds now represent more than 50% of assets under management. In addition to a broadly diversified product portfolio, AllianceBernstein has three well-developed distribution channels in its institutional, retail, and private banking lines; all posted good net inflows during the third quarter. The firm's depth and breadth of products and services gives it a competitive edge over smaller rivals, while cushioning the potential impact of a downturn in a market or investing style.

Though AllianceBernstein's competitive strengths make it a leader in the asset management industry, its operating performance does not justify the huge returns on its stock. The firm's growth in assets under management is similar to the growth rates experienced by such rivals as Affiliated Managers Group (NYSE:AMG) and T. Rowe Price Group (NASDAQ:TROW). AllianceBernstein's revenue growth was largely flat in the third quarter. Its partnership units, though, trade at a rich P/E multiple--especially when compared to the multiples of its rivals' shares.

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Fool contributor Michael Leibert welcomes your feedback. He holds no financial position in the shares of any of the companies named in this article.