Broker Carnegie said it still sees upside in AstraZeneca's share price despite a takeover by Pfizer now looking unlikely.AstraZeneca's shares fell as much as 14% on Monday morning after the board rejected a sweetened £55-a-share bid from Pfizer. The new offer is thought to value AstraZeneca at around £69bn but was only a "minor improvement" on previous proposals, according to Chairman Leif Johansson.Pfizer said this is a "final proposal" and would not be increasing it any further. It said it would not pursue a hostile offer and would only announce another offer with the recommendation of AstraZeneca's board."Although AZN's board was prepared to recommend an offer above £58.85, the fact that Pfizer has so clearly stressed this was their final bid and that it would not go hostile means the likelihood for a deal is now very small," Carnegie said in a research report."At the same time, R&D news has been very positive in the past month, which explains why the share price is not trading down to the levels before the bid."The broker maintained its 'buy' recommendation on the stock, which was trading 12.1% lower at 4,238p by 10:34 on Monday.BC