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 mutual-fund manager Janus Capital Group (NYSE: JNS) were flying high today, gaining as much as 18% in intraday trading after the company announced a big investment from Japan's Dai-ichi Life Insurance.

So what: Dai-ichi is stepping in to buy up to 20% of Janus, a move that could cost the insurer around $300 million. Along with the investment, Dai-ichi is also putting $2 billion of its clients' money into Janus' funds -- that's something but not a huge needle-mover -- and will start to sell Janus-family funds through DIAM Asset Management, a joint venture between Dai-ichi and Mizuho Financial. Dai-ichi will also get a seat on Janus' board.

Now what: There's good reason for Janus shareholders to be excited about this. For one, we've got a major financial company spending a significant amount of money to buy a stake in Janus. That means that either Dai-ichi likes throwing away money or it sees an opportunity in Janus shares. It's a vote of confidence and confirmation bias for Janus bulls all rolled up into one.

At the same time, the deal gives Janus a nice sales outlet in Japan. That could be one of the more notable aspects of the deal since the company has been struggling with investors pulling money out of its mutual funds and could really use some new avenues to attract investor dollars.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.