Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of investment decision support software company MSCI (Nasdaq: MSCI) are imploding today, currently down 30%, following news that MSCI would be losing one of its largest clients, the Vanguard Group.

So what: Citing cost savings as the main impetus, Vanguard Group, the United States' largest mutual fund manager, said it would be switching 22 of its largest funds away from the benchmarks provided by MSCI. In total, $537 billion in assets under management will be shifting away from MSCI's benchmarks to those developed by the University of Chicago's Center for Research in Security Prices.

Now what: This might appear to be dire news given Vanguard's premier name, but MSCI seems to be more than paying its penance. Vanguard provided MSCI $24 million in operating income last year, whereas the remaining $7 trillion in assets currently benchmarked to MSCI's indexes tallied an additional $298 million in operating income for MSCI. The real concern here is what happens if other mutual funds get the same idea. I'm not ready to jump on board yet, but this could be a clear case of an overreaction if MSCI continues to head lower.

Craving more input? Start by adding MSCI to your free and personalized watchlist so you can keep up on the latest news with the company.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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