expert david menlow says it's not a coincidence that many are well-known names. >> the new trends that are emerging in this i.p.o. market certainly point to investors not having any patience for stocks that need an explanation, any more than a sentence of two. name recognition, brand i.d. is critical for many of these offerings at this particular point. >> reporter: the i.p.o. market has picked up steam since linked in debuted two weeks ago. the $1.3 billion raised makes it the most successful i.p.o. since google. but many in the class of 2011 have struggled in the after- market. shares of linked-in, for example, are down almost 17% from their first day close. analyst rich peterson explains why. >> we've seen some companies give up their first-day gains, though they are still trading above their offering price. so, in a month where may was having trouble, the s&p off about 3% or so, some of these companies that recently debuted have retreated a bit as the market has also. >> reporter: 83 companies have gone public so far this year, up from 58 this time last year, a more than 40% increa