JPMorgan to Buy Stake in Highbridge Fund  NEW YORK (Reuters) - J.P. Morgan Chase   Co. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=JPM.N target=/stocks/quickinfo/fullquote"&gt;JPM.N&lt;/A&gt; plans  to buy a majority stake in the hedge fund Highbridge Capital  Management, the companies said on Monday, a sign that Wall  Street is seeking a bigger role in the rapidly growing  hedge-fund industry.