If there are any worries about the future of biotech, don't tell the venture capitalists.

Last week, biotechnology firms raised $758 million from VCs and angel investors, according to an analysis by Pitchbook, a data provider that tracks venture and private equity investments. In the year-to-date, venture capitalists have poured $2.8 billion into biotechnology startups. That means that in the first two months of 2018, venture capitalists have invested more in biotechnology firms than they did in all of any year before 2014.

And that may be an underestimate: the PitchBook list does not yet include Gelesis, which announced a $30 million fundraise last week, or health tech companies like Nomad Health (raised $12 million) or Woebot (raised $8 million).

It's not that there are that many more deals. Instead, investors are putting up much larger sums of money. They are pouring hundreds of millions of dollars into companies long before they are due to sell stock on public markets. In 2013, the VC community spread $2.4 billion among 287 companies. The $2.8 billion spent in two months of 2018 went to just 60 start-up firms.

Last week was no different. The average investment was $84 million, with three companies raising more than $100 million. Helix, a competitor to 23andMe and Ancestry in consumer genetics, raised $200 million ($50 million less, it's worth noting, than 23andMe raised in September). Viela Bio, an AstraZeneca spinout, raised $250 million. Rubius, a cell therapy chaired by former Novartis pharmaceuticals executive David Epstein that focuses on turning red blood cells into drugs, raised $100 million despite not having started human tests.

And, as a consequence, these companies are now more valuable than privately held firms have ever been. A company is literally worth the sum of the price of all its shares. For public firms, this figure is the market capitalization. For private firms, the number can be fuzzier, with investors cutting special deals in which some shares are worth more than others, thereby inflating valuations. It's also true that sometimes these big headline fundraises come in tranches, meaning the company can't actually access all the money at once.

Still, the big numbers for these companies are stunning. Samumed, a regenerative medicine firm profiled on the cover of Forbes, counts Trump economic advisor Gary Cohn among its backers. Its valuation, based on a 2016 round? $12 billion, more than any publicly traded biotech firm without approved drugs. "At the company level at this point, as you pointed out, our valuation is already an eye opener," Samumed's founder, chairman and chief executive, Osman Kibar, said at the Forbes Healthcare Summit in December 2016. "For a pre-revenue company at that valuation, it's just impossible for us to get a fair market cap if we were try and go public today."

When it comes to high-valuation companies, they tend to be doing things other than developing drugs, which is where biotechnology firms have traditionally delivered big returns. There is Moderna, which is trying to develop a whole new type of drug that works on RNA, a genetic messenger chemical, not proteins. It's valued at $7 billion. But other billion-dollar-plus private companies (often referred to as "unicorns") include: 23andMe; Human Longevity, the DNA sequencing firm backer by Craig Venter; and Indigo Agriculture, focused on altering soil bacteria to improve crop yields.

Most Valuable US VC-Backed Biotech Companies by Post-Valuation