US STOCKS-Janus has best day in its history as Gross joins ranks

* Indexes up: Dow 0.4 pct, S&P 0.2 pct, Nasdaq 0.3 pct

By Ryan Vlastelica

NEW YORK, Sept 26 (Reuters) - Shares (Berlin: DI6.BE - news) of Janus Capital (NYSE: JNS - news) soared on Friday, with the stock on track for its best one-day advance in its history, after Janus said famed bond investor Bill Gross would join the company.

The stock surged 33 percent to $14.79 on volume of 79.6 million shares, many times its 50-day average of 2.3 million and making for the most active day in the stock's history. With the day's advance, Janus shares moved to their highest level in more than four years.

Gross's move came as a surprise. A source familiar with the matter told Reuters that the development came a day before Pimco and its parent, German insurer Allianz SE (Other OTC: ALIZF - news) , planned to dismiss Gross.

The Pimco High Income Fund fell 6.8 percent to $11.60 on heavy volume, while the Pimco Total Return ETF was down 0.3 percent to $108.64.

Index snapshot at 12:12 EDT:

* S&P 500 was rising 4.48 points, or 0.23 percent.

* Nasdaq Comp was gaining 15.00 points, or 0.34 percent.

* Dow industrials was adding 64.48 points, or 0.38 percent.

* Russell 2000 was adding 3.59 points, or 0.32 percent.

* S&P MidCap was adding 3.16 points, or 0.23 percent.

* S&P SmallCap was gaining 0.89 points, or 0.14 percent. (Editing by Nick Zieminski)