Lance Whitney/CNET

With its steady stream of daily deals, Groupon has seen an increase in both subscribers and sales, but the company continues to rack up a string of net losses, reporting a second-quarter deficit of more than $100 million, according to a filing yesterday with the Securities and Exchange Commisson.

Compared with a net loss of just $35.9 million a year ago, the latest downturn comes as the company has spent a lot of cash to increase staff and venture into new markets, notes The Wall Street Journal's MarketWatch.

Groupon's workforce has surged to 9,625 employees as of June 30, 2011, from just 37 as of June 30, 2009, according to the SEC filing. The company also expanded to 175 markets in North America and 45 different countries from just five North American markets in June 2009.

Though all that expansion has taken its toll on the bottom line, Groupon did manage to bump up its revenue to $878 million in the second quarter, compared with $3.3 million in 2009's second quarter. The number of subscribers has surged to 115.7 million this past June from 152,203 in June 2009.

But overall, the continued net losses may be a sign of both "merchant fatigue and customer fatigue," according to financial news site Minyanville, quoting marketing strategist Rocky Agrawal. In a story for TechCrunch, Agrawal said he thinks Groupon is "poised for collapse."

The net losses could also affect Groupon's valuation as the company tries to go public.

Opening its doors in October 2008, Groupon filed an initial public offering this past June, with the intention of raising $750 million to fund its ongoing growth. But the company decided to amend its S-1 filing with the SEC after it was criticized for using a controversial accounting metric called ACSOI, or adjusted consolidated segment operating income, which can fudge the numbers by leaving out certain expenses.

As a further blow, Groupon has been facing increased competition from other companies offering daily deals, including Google, which unveiled its Google Offers earlier this year.