Analysts at Jefferies are estimating that pharmaceutical company AbbVie could find itself a deal if it sweetens its $46 billion takeover offer for London-listed rival Shire. Jefferies analysts estimate that AbbVie could improve its offer to 55 pounds a share, or $55 billion. That's up from its most recent cash-and-shares offer of just over 46 pounds, which was rejected. Shire has argued that AbbVie's offer undervalues its business. Since the offer, Shire is giving long-range forecasts for its drugs, predicting that its $4.9 billion in sales in 2013 may double to $10 billion by 2020, helped by its successful ADHD treatment.