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 Riverbed Technology, (UNKNOWN:RVBD.DL) popped 11% today after activist hedge fund Elliott Management Corp. offered to buy the networking gear maker for about $3.1 billion.

So what: The all-cash offer values Riverbed at $19 per share and represents a premium of 6% to yesterday's close price. Elliott -- which already owns a 10.5% stake in the company -- is making the move as it clearly sees Riverbed as undervalued, but with the stock already trading above its $19 offering price, Mr. Market is betting that this is just the first step in the value-boosting process.

Now what: Expect Elliott's offer to prompt higher bids in the near future. "To this point, we believe other strategic and financial buyers could enter the Riverbed bidding process over the coming months as this remains a core strategic asset within the broader technology food chain," FBR Capital analyst Daniel Ives wrote in a note to clients. Of course, unless you'd be perfectly willing to own Riverbed as a long-term investment, it's probably best to watch the process unfold from the sidelines.