Looking back at 2015, it's wild how quiet that year was for IPOs compared to what we'd seen before. Only 169 companies went public that year, which was nearly 40% fewer than 2014. The money raised dropped even more dramatically - down to $30 billion from $85 billion the year before. Market sentiment had cooled considerably, and a lot of companies that were hyped up, like Uber, just decided to stay private and raise capital that way instead.

But among the companies that went public in 2015, there were definitely some standouts. On the winner side, Spark Therapeutics absolutely crushed it. This gene therapy company for retinal diseases priced at $23 and then soared 122% by the end of the year. They initially planned to price between $19-$21, but demand was just too strong. The real kicker came when they announced positive late-stage trial results in October.

Seres Therapeutics was another biotech that more than doubled. Started at $18 and ended up 106% higher by year-end. The microbiome therapeutics space was getting real attention, and even though they were still burning cash, investors felt good about their runway extending into 2017.

Then there was Shake Shack. The burger chain that went public in January at $21 absolutely captured people's imagination. By May it had hit $96.75. Sure, it came back down from those peaks, but anyone holding on still had a solid 105% gain. The comparable sales numbers showed the concept was genuinely resonating.

Now for the painful part. MaxPoint Interactive hit the market at $11.50 and proceeded to lose 88% of its value. Their Digital Zip marketing technology was actually growing revenue - up 33% in one quarter - but the losses kept expanding. You could see the market's patience wearing thin.

Zosano Pharma's transdermal microneedle patch technology seemed promising at $11, but it shed 77% of its value after they scrapped their osteoporosis program and ended a partnership. That September announcement basically killed the momentum.

Belloran Pharmaceuticals rounded out the disaster list, dropping about 75% despite initial investor excitement around their pulmonary hypertension treatment. It's always been this way with IPOs - companies that went public in 2015 showed us that biotech especially can be a rollercoaster. You get winners that deliver real clinical results and massive gainers, but you also get companies that just can't execute on their promises. The broader market was definitely more selective that year, which probably explains why so many debutantes struggled.