Struggling online deals pioneer Groupon has fired its quirky founder and chief executive Andrew Mason.

The move comes amid worries that people are tiring of the online restaurant, spa and Botox deals that Groupon built its business on.

In a refreshingly candid memo to staff, Mason said Groupon's employees "deserve the outside world to give you a second chance. I'm getting in the way of that. A fresh CEO earns you that chance."

Shares jumped over 4% in extended trading following last night's announcement, which had been anticipated for months.

Executive chairman Eric Lefkofsky and vice chairman Ted Leonsis were appointed to the Office of the Chief Executive while a replacement is found.

In his memo, Mason referred to controversy over the accounting practices used in regulatory filings ahead of Groupon's November 2011 initial public offering of stock as well as "two quarters of missing our own expectations and a stock price that's hovering around one quarter of our listing price."

"The events of the last year and a half speak for themselves," he wrote. "As CEO, I am accountable."

The announcement came a day after Groupon reported a bigger than expected loss and gave a weak revenue outlook for the current quarter.

The guidance had fueled investor worry - which started even before Groupon's IPO - that people are suffering from fatigue over the frequent emails flooding subscribers' inboxes.

There were also worries that the company's efforts to broaden into an e-commerce powerhouse have not been paying off. Groupon makes money by taking a cut from the online deals it offers on a variety of goods and services.

Investors have questioned whether that business model is sustainable and leads to growth over the long term - and whether the company can not only grow its customer base but make more from each subscriber.

Groupon had the advantage of being first, but the model is easy to replicate. It has spawned many copycats after its 2008 launch, from startups such as LivingSocial to established companies such as Google and

Chicago-based Groupon also has faced scrutiny about its high marketing expenses, enormous employee base and the way it accounted for revenue.

Mason, a Northwestern University graduate and former punk band keyboardist, founded Groupon in 2008. By 2010, Groupon was available in 25 countries and its staff ballooned to nearly 10,000, many times that of other Internet darlings such as Twitter, Facebook or Zynga, the other fallen star of the latest swath of Internet IPOs.

Groupon's stock has lost about 77% of its value since the IPO after losing $1.45, or 24%, to close at $4.53 last night.