DocuSign's initial public offering has been welcomed by stock-market investors. CNBC reported the company raised $629.3 million after pricing shares at $29, above the $26 mark that was expected. The stock is now up to $39 on the Nasdaq, and the company's valuation is $4.4 billion.

DocuSign's IPO experience has been pretty much what the company expected, according to CEO Dan Springer. "We were optimistic that it was going to be very straightforward because of our very strong financials and results," he told Inc. It's worth noting the company--no spring chicken--took its time getting to this point. "It's been 15 years," Springer said (although he himself joined in January 2017). "It's been a long time coming, in a good way."

Springer said DocuSign's warm reception demonstrates investors' appetite for SaaS stocks. "The marketplace has a supply-demand imbalance right now, where there's a lot of enthusiasm for cloud-based businesses," he explained. This dynamic is driving the ongoing surge of B2B tech IPOs in 2018. "Investors are looking for more product to buy," Springer said.

Recent strategic acquisitions like Salesforce buying MuleSoft and Square buying Weebly are another expression of underlying demand. The M&A teams at big firms, it would appear, are just as enthusiastic about enterprise software as the public markets.