The technology bubble may have burst more than 15 years ago, but large law firms are still taking equity stakes in startup companies that they help bring to market.

When Cooley took the lead last month on an initial public offering for Snap Inc. valuing the ephemeral messaging service at $33 billion, documents filed with the U.S. Securities and Exchange Commission showed that the firm owned shares in the company worth $11.7 million.

The Snapchat owner's IPO marked nearly two decades of Cooley taking stakes in its clients—a practice that proved wildly profitable for the firm and other Silicon Valley stalwarts during the dot-com era. Although firms today are not nearly as aggressive in pursuing stakes in emerging companies, many are still scooping up sizeable portions of stock in certain clients through affiliated investment entities. Snapchat wasn't Cooley's only recent client investment.