After some timing drama, daily deal site Groupon finally has begun trading on the NASDAQ this morning, in the most hotly anticipated and largest Internet company IPO since Google. The company — which trades under the ticker $GRPN — priced its shares at $20 last night, but began trading at $28, an increase of 40%.

Like LinkedIn, Groupon is only floating a small amount of shares,  35 million – about 5.5% of its 637.3 million shares outstanding. The first trade would pin its market cap at 17.8 billion, with a 980 million raise.

Groupon filed its S-1 in early June and since has a had a bumpy road to today’s IPO, with negative press coverage (including) and reports of drastically decreased pricing plaguing the three-year old company.

Its revenues on its S-1 for 2010 were adjusted from $713 million to $313 million due to errors in reporting. Its total revenues for the first half of 2011 were reduced from $1.5 billion to $688 million due to the same adjustment. The company turned down a $6 billion offer from Google late last year.

The company lost $420 million last year and $117.1 million in the first quarter of 2011 mainly due to expansion and marketing costs — a fact that does not go unnoticed by potential investors and armchair Twitter pundits many of whom could not resist the “sign of a bubble/apocalypse” talk or lame deal jokes this morning.

It’ll be interesting to observe the stock’s performance today, to say the least.

Update: It looks like the pop has dropped in the first 20 minutes of trading, now hovering around $26. Stay tuned!

Pic via Julie_Mo/Emily Chang