Mobile payments company Square is officially trading on the stock market today, a little over a month after filing paperwork to go public. The company, led by CEO Jack Dorsey, will now trade on the New York Stock Exchange under the symbol SQ. It priced last night at $9 a share, the bottom of its range, a clear sign that investor interest and confidence was lacking. It's been trading up since opening, rising to $11.20 by midday.

Square's IPO was a long time coming. Since its debut in 2009, the company's Square Readers have flooded small businesses as an easy means of processing credit card payments. The company processed $23.8 billion in payments last year alone, and had signed major deals with retailers like Starbucks. That kind of clout has kept investors interested in a seemingly inevitable public offering over the years.

However, Square still stands on shaky ground. Earlier this month, the company set its price range at between $11 and $13 a share, only to scale back to $9 yesterday. Now worth $2.9 billion, the company is worth significantly less than the massive $6 billion valuation it held last year after a private funding round. The leaner IPO is already stoking fears that the Silicon Valley bubble is starting to deflate.

Another concern, as ever, is Jack Dorsey's role at Twitter. Dorsey was just installed as permanent CEO at the social network last month, and his role there going forward is to ensure the company can grow its audience. The company recently announced that it had added only 4 million unique users in the last quarter. Building Twitter and innovating atop the platform will require Dorsey attention — the kind of attention Square has already acknowledged will distract him from Square's business.