We've already got 4 huge biotech mergers this week

The week has started with four massive biotech deals.

Here's the breakdown:

• Horizon Pharma will buy all outstanding shares of Hyperion Therapeutics for $46 per share in cash, or about $1.1 billion. The deal will expand Horizon's portfolio of drugs for a rare metabolic disease, according to a statement.
• Cellular Dynamics International has agreed to be acquired by Tokyo-based FujiFilm Holdings for $16.50 a share or about $307 million, the companies announced Monday. Cellular Dynamics is "a leading developer and manufacturer of fully functioning human cells in industrial quantities to precise specifications," and had revenues of $16.7 million in the 2014 financial year. It surged by as much as 111% in pre-market trading.
• Teva Pharmaceuticals will acquire Auspex Pharmaceuticals at $101 per share in cash. "The acquisition of Auspex is a significant step in strengthening Teva's leadership position in [the Central Nervous System franchise] and advances us into underserved movement disorder markets," the companies said in a statement.
  
• And finally, UnitedHealth will combine its pharmacy benefits unit with Catamaran Corp. to form a new competitor in the industry. UnitedHealth will buy out Catamaran for $61.50 per share in cash.

After an ugly selloff last week, the iShares Nasdaq Biotechnology ETF is over 1% higher in pre-market trading.

On Friday, Citi analysts laid out some compelling arguments for why biotechs are in a bubble, and then concluded that it is not.

The industry is in a new era where actual earnings and profits accompany the "hopes and dreams" that their inventions are usually associated with.