Activist hedge fund Elliott Management Corp offered to buy network equipment maker Riverbed Technology Inc for about $3.08 billion in cash, an offer analysts said was likely to be a precursor to a higher bid. Riverbed shares rose as much as 14 percent to $20.29 on Wednesday, above Elliott’s offer price of $19 per share. Gabelli & Co analyst Hendi Susanto said the offer was below his valuation of $25 per share for Riverbed, based on 14 times 2014 earnings. Elliott affiliates said in November that Riverbed was significantly undervalued and should consider a strategic review.