RANKED: Here are the best and worst pharma deals of the past decade, and why they tanked or triumphed

• Over the past 10 years, major acquisitions have reshaped the healthcare industry.
• Analysts from SVB Leerink rounded up the five best and the five worst pharma deals of the last decade.
• One of the best deals was Merck acquiring Schering-Plough for $41 billion in 2009, with one of the worst deals being Johnson & Johnson's $30 billion acquisition of Actelion in 2017, according to the Leerink analysts
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Over the past 10 years, dealmaking has reshaped the pharmaceutical industry.

Facing generic competition for once-blockbuster drugs and new pricing threats, many a deal got done to fill in key gaps in a company's portfolio - some more successfully than others.

Analysts at SVB Leerink rounded up the five best and the five worst acquisitions of the last decade. The list of best and worst deals are based on an analysis of all the transactions over the last decade along with the input of the SVB Leerink therapeutics research team, and it shines some light on the often binary nature of biotech dealmaking.

The analysts found overall that deals with a transaction value of $1 billion to $5 billion have the highest success rate, compared to lower success rates for larger transactions. The analysts note that deals within the oncology space had two times the success rate as deals in other therapeutic areas.

The best deal was Merck acquiring Schering-Plough for $41 billion in 2009, and the worst was Johnson & Johnson's $30 billion acquisition of Actelion in 2017. The gains made by the top deals towered far over the losses of the bottom five, according to Leerink's estimates.

Read on to find out what contributed to the best and worst pharmaceutical acquisitions of the last decade.