A stretch of initial public offerings surging in their debuts grew more dramatic on the last Thursday in June, with a pair of record-breaking pops from the health sector that included the best start of any 2019 new offering: Bridgebio Pharma Inc. (Nasdaq: BBIO) opened 80 percent above its IPO price, the biggest opening gain by any biotech or pharma public debut this year, according to Bloomberg News. Adaptive Biotechnologies Corp. (Nasdaq: ADPT) opened even higher. Shares traded at nearly double their IPO price, surpassing CrowdStrike Holdings Inc. (Nasdaq: CRWD), to become the year’s biggest pop from any sector. CrowdStrike opened 87 percent above its IPO price on June 12.

A dam of pent-up venture capital-backed initial public offerings seemed to burst in the second quarter, with 62 U.S. IPOs—the highest quarterly count in four years — raising $25 billion—the highest quarterly amount in five years, according to Renaissance Capital. Now, VC investors are watching to see if the stock market returns from the 2019 crop of IPOs — including Uber (NYSE: UBER), Lyft (Nasdaq: LYFT) and Slack (NYSE: WORK) — justify the hype.

Investment lockups mean that it generally takes two quarters after an IPO before the VC backers of a company that goes public can measure their full returns: the initial valuation plus (or minus) its gains or losses as it is publicly traded. But at least for the VC investors of the companies that went public in the second quarter, the trend is favorable: The average return for those companies for the quarter was 30 percent, led by plant-based meat protein maker Beyond Meat’s (Nasdaq: BYND) stock reaching 542 percent above its initial price, Renaissance reported.

Until recently, the U.S. VC market has been so awash in capital that more and more VC-backed companies have chosen to put off their day of reckoning—exits for VC investors through IPOs or M&A—in favor of taking on additional rounds of VC funding instead, says Bob Blee, head of corporate finance at Silicon Valley Bank. “There is ample capital in the market, both from traditional and non-traditional investors, that valuations and rounds continue to climb, allowing companies to stay private longer,” he says.

In 2018, a record $131.5 billion was invested in U.S. venture capital deals, and VC investment funds raised $55.5 billion, also a record, according to Dow Jones VentureSource. Those trends have continued in 2019: $31.5 billion was invested in VC deals in the first quarter, according to the most recent figures available. That was the third-highest quarterly total since Dow Jones began tracking VC figures in 1992, ranking behind only the third and fourth quarters of 2018. VC investment funds raised $15.5 billion in the first quarter of 2019, also the third-highest quarter on record, trailing only the second and fourth quarters of 2018.

The high-profile VC exits so far this year could signal a shift toward more IPOs for other VC-backed companies, however. A slew of IPOs for unicorns—privately held companies valued at more than $1 billion–is slated this year, so investors in VC funds are anticipating that 2019 will be the year of strong distributions, not just paper returns, says Maryam Haque, senior vice president of industry advancement for the National Venture Capital Association, a VC trade association headquartered in Washington, D.C.

The fate of the IPOs is shaping up to be the most compelling VC story of 2019, Blee says. “The most interesting story to watch is to see how these unicorns, which have been private for so long and have so much hype around them, perform in the public markets post-IPO,” he says.

Venture capital industry watchers are also interested in how much of the IPO returns are cycled back into new VC investments, Haque says.

The first half of 2019 has been filled with prominent IPOs. CrowdStrike, the cybersecurity company, was one of the most notable recent IPOs, valued at $11.4 billion with its initial offering in June. By the end of the month, the stock was up 15 percent. Also in June, software company Slack was initially valued at $23 billion, and its stock had risen 39 percent.

For the first quarter, Uber’s IPO was the largest VC exit, announced with an initial valuation of $75 billion. Lyft’s initial valuation was $24 billion—the second largest of the quarter. Pinterest (NYSE: PINS), Zoom Video Communication (Nasdaq: ZM) and PagerDuty Inc. (NYSE: PD) rounded out the top five VC exits, as measured by Silicon Valley Bank, with initial valuations of $10 billion, $9 billion and $2 billion, respectively.

Not all debuts have soared. Uber’s stock was down 1 percent through the second quarter, and Lyft’s was down 12 percent. Pinterest was up 38 percent, and Zoom Video rose a whopping 140 percent.

The momentum is expected to continue in the second half of the year, including expected debuts from entertainment company Endeavor Group, office-space-sharing business the We Co., also known as WeWork, and the Peloton exercise company.

While the VC market has set records for investment totals and fundraising, the number of VC deals had been trending down before the second quarter —making some analysts wonder of investors were becoming more cautious due to uncertainty about the global macroeconomic environment, says Cyril Neant at Dow Jones VentureSource.

The number of VC deals dropped to 1,234 for the first quarter of 2019, down 23 percent from one year earlier and the third straight quarterly decline, according to Dow Jones VentureSource. That kind of decline has occurred only twice before: during the 2008-2009 financial crisis and during the bursting of the dot-com bubble in 2001. Whether the drop is a statistical anomaly or an indicator of things to come is unknown, according to the report.

Blee predicts the trend of fewer-but-larger VC deals will continue in 2019, perpetuating a “haves vs. have-nots” situation where the “haves” will continue to attract larger rounds of venture capital at a quicker clip. Meanwhile, the “have-nots” may have to accept investments from less-desired partners or seek exits through sales to private equity. The trend could also signify a flight to quality, with VC investors picking the market leader and potential biggest winner to justify investing capital at ever-growing valuations, and on top of major capital stacks, Blee says. Unlike the VC market, both the number and total value of middle-market PE deals have continued to climb into record territory, up more than 15 percent in 2018, according to Silicon Valley Bank figures.

One factor driving the large amount of investor capital in VC is the wide range of new sources of capital beyond traditional funds, Haque says. The London-based SoftBank Vision Fund, a $100 billion VC funding vehicle that launched in 2016, has been a game changer in the venture capital space by making large pools of capital available to later-stage venture companies, and sovereign wealth funds, hedge funds and family offices have become more active in VC, she says. Also, large venture funds have grown larger while many small, first-time VC funds have launched, creating a barbell effect on the fund landscape.

Corporate venture capital funding has also increased over the last two years, both from many new corporate venture firms and traditional sources like Salesforce Ventures, the VC arm of Salesforce.com Inc. (NYSE: CRM) that launched in 2009; Alphabet Inc.’s (Nasdaq: GOOGL) GV, formerly Google Ventures; and Intel Capital, the VC and M&A investment division of Intel Corp. (Nasdaq: INTC).

A look at the first quarter shows the role corporations are playing in backing startups. The top three venture capital investments in the first quarter of 2019 were funded by SoftBank Group, according to figures compiled by PitchBook-NVCA Venture Monitor. SoftBank invested $5 billion in WeWork, and $940 million in Nuro, a Silicon Valley deliveries-by-robot startup. SoftBank was part of a group investing $1 billion in San Francisco-based Flexport Inc., a sea and air freight shipping broker. Others in that group were San Francisco-based Susa Ventures, an early-stage VC firm; China-based Cherubic Ventures, an early-stage tech-focused VC firm; SF Express, a Chinese delivery services company; Hong Kong-based DST Global, an Internet services focused VC firm; and Founders Fund, Peter Thiel’s San Francisco-based VC firm. Amazon.com Inc. (Nasdaq: AMZN) was an investor in the fourth and fifth-largest VC deals of the first quarter: $700 million in Rivian Automotive Inc., a Michigan-based electric pickup truck and SUV startup, and as part of a group investing $530 million in Palo Alto, California-based Aurora, a self-driving car startup.

If IPOs perform as well in second half of the year as many have in the first half, VC firms and corporations will likely increase in their investments in startups.