Venture capitalists have become much pickier than they once were, are taking longer to invest and are writing bigger checks.

Why it matters: It's harder for startups to raise money, even though investors are flush with cash.

All of the below data comes from PitchBook — including some from the Q4 PitchBook-NVCA Venture Monitor— unless otherwise noted:

Barbell Effect

Today's seed rounds are yesterday's Series A rounds, which have become yesterday's Series B rounds, and so on. This has led to a hollowing out at the earlier stages of investing, as many firms have gone even more amoebic (so-called "pre-seed") while others have gone later.

• There were only just over 3,793 seed deals in 2017, compared to more than 4,375 the previous year, and 5,680 in 2015.
• Some seed investors have moved over to the cryptocurrency market, with initial coin offerings raising more than $3.7 billion last year, per Coinschedule.
• In 2017, the median age for startups raising seed rounds was 2.42 years old—about a year older than in 2008 and half a year older than in 2014. Companies raising Series A and B are seeing similar trends.
• In 2017, more than 60% of all late-stage capital invested was in deals of $50 million or more—the highest proportion in the last decade.

Bigger deals, longer waits

• The median U.S. seed deal in 2017 was $1.7 million, up from $1.47 million in 2016, and $1 million in 2015.
• Median early-stage rounds (Series A and B) in 2017 were $6.0 million, up from $5 million in 2016, and $4.38 million in 2015.
• The average check size for Series A and Series B investors has increased by 36% over the past decade, while the average number of investors in such rounds has climbed by 40% (as of Q3 2017).
• In 2017, First Round Capital reports that 34.1% of its portfolio companies took more than four months to raise new funding, up from only 25% in 2016, and 20% in 2015.

Unicorn watch

Later-stage companies continue to stay private longer, aided by continued access to "crossover" investors and an uptick in secondary liquidity deals for early employees and investors.

• $575 billion worth of unicorn tech startups remained private through the end of Q3 2017.
• The median time between a startup's first VC funding and its IPO hit 8.1 years in Q3 2017, up from about 6.5 years in 2010.
• The decline in new VC deals is being outpaced by the decline in exits, whether via IPO or acquisition.

Top-line data

U.S. venture capitalists invested $84 billion into 8,035 companies in 2017, up from $72 billion in 2016 and the highest annual total since the dotcom era.