Shares of Lyft were slightly negative by the end of trading Tuesday, marking its third day on the public market. The shares were still trading below their IPO price of $72, at $68.97 per share. Trading volume for Lyft was high, and the stock bounced between positive and negative territory throughout the the day.

Tuesday marked the second day of losses for Lyft, which ended its second day of trading Monday at $69.01, below its IPO price of $72 in an oversubscribed offering. Lyft's market capitalization now lies below $20 billion after ending its first trading day at $22.2 billion.

Analyst skepticism sent the stock down as much as 4 percent in premarket trading Tuesday, with Seaport Global Securities initiating coverage of the stock with a sell rating and 12-month price target of $42 per share.

"In order to justify its current market valuation, investors need to take a big leap of faith that the millennials and later generations will forego ownership of a car and opt instead for reliance on a ridesharing service," the analyst wrote in a note Tuesday morning. Instead, he said ride-sharing will continue to be used as a "convenient supplement."

Lyft's stumble may be troubling to some investors, but based on previous tech stock debuts, it's too early to tell what this first week will mean for the stock. Snap debuted in 2017 with a $24 billion valuation, but has slid to just $15 billion. Twitter's market capitalization has not changed much since its market debut in 2013, which was about $25 billion at the end of its first day of trading. Today, it's market value is about $25.7 billion.

Meanwhile, Facebook's stock plunged 11 percent on its second day of trading in 2012 after being valued at over $100 billion in its IPO, but today the company is worth more than $481 billion.

Lyft's rapid growth fueled by private funds could leave little room for new stockholders to gain from its public offering. Dropbox, similarly, went public last year with a market value of $8.2 billion and is now around $8.8 billion with its shares little changed from their $21 IPO price.

Without a clear counterpart on the public market, Lyft remains difficult to evaluate. Investors know Lyft's main rival, Uber, is much larger, with an expected valuation of over $100 billion. But since it hasn't yet released its prospectus, it's hard to say how its financials stack up to Lyft's. Uber did release unaudited financials for 2018. The company said it generated $11.3 billion in revenue, up 43 percent year over year. It also posted adjusted losses of $1.8 billion, down from $2.2 billion in 2017.

There is also the remaining risk of imbalance after Lyft's lock-up period ends. Currently, only 11 percent of Lyft's outstanding shares are available for trading, while employees and early investors are required to wait six months to sell their shares. But if too many shares flood to market, the company runs the risk of not having enough buyers to meet the supply.

Still, other tech companies will be looking to Lyft's performance and the public reaction as they prepare their own public offerings. Lyft's rival Uber is expected to drop its S-1 this month and go public a few weeks after that. And a number of others, including Slack, Pinterest and Zoom, are expected to hit the public market this year as well.

-CNBC's Ari Levy contributed to this report.

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Watch: Lyft shares slump 12% on second day of trade