Image source: Intersil Corp.

What: Shares of Intersil Corp (NASDAQ:ISIL) were up 19.9% as of 12:30 p.m. Monday following reports that Japan's Renasas Electronics Group is interested in acquiring the U.S.-based semiconductor specialist.

So what: Specifically, Reuters cited an unnamed "industry source familiar with the deal" as stating Renasas "is in the final stages of negotiations to acquire [Intersil] for as much as 300 million yen," or just under $3 billion.

Now what: Today's pop brings Intersil's market capitalization to around $2.6 billion as of this writing, leaving around 15% upside for investors willing to stick around with the hope Intersil is able to make the most of the reported negotiations. With shares already up nearly 50% year to date, however, and keeping in mind nothing is finalized yet, I think Intersil investors would be wise to take at least some of their chips off the table today.