Get ready to bust out your flask of unicorn tears.
So-called “unicorns”—startups valued at $1 billion or more—are breeding like bunnies these days. Hot and bothered, venture-backed bunnies. In fact, Fortune counts some 140 of these hopeful, hopped-up monsters on our own “Unicorn List,” up from 80 when the magazine first wrote a cautionary cover story on “The Age of Unicorns” at the beginning of the year. That spike in investor spending raises an uneasy, VC-queasy question: Are we in a tech bubble?
The brains here at Fortune HQ ponder this question often, to be sure. It certainly seems as though something funky is going on in the private markets. But don’t just take our word for it. Fortune opened the floor to another set of influential insiders: our new 40 Under 40.
Here, then, the top young-guns of our generation weigh in: Bubble, or not?
James Park, Co-founder and CTO, FitBit (No. 5)

Much like Schrödinger’s cat, I feel that if we don’t look too closely, we are simultaneously in a tech bubble and not in a tech bubble.
Stacy Brown-Philpot, COO, TaskRabbit; Boardmember, HP Inc. (No. 29)

“I consulted my four year old daughter about this and she tells me it’s not possible to have this many unicorns.”
Hugo Barra, Vice president, Xiaomi Global (No. 14)

Data does not show a tech bubble. Today's tech companies are supremely more sound and mature than the IPOs of 1999.
Sam Altman, President, Y Combinator (No. 30)

No. We’re in a government / interest rate bubble that inflates value of everything. Tech no more so than anything else.
Brian Sheth, Co-founder and president, Vista Equity Partners (No. 33)

Yes.
Jared Kushner, CEO, Kushner Companies (No. 25)

No. We are in an industrial revolution, which makes it hard to value the future potential of these globally transformative businesses.
Kayvon Beykpour, Co-founder and CEO, Periscope (No. 18)

I think we're in more of a psychological bubble than an economic one, especially in the private markets.
Julia Hartz, Co-founder and president, Eventbrite (No. 36)

This is a special time in Silicon Valley - both good and bad.
Jason Buechel, CIO, Whole Foods (No. 10)

Yes, I believe we are in one. One area of the bubble I’m watching closely is online meal kit delivery services (Blue Apron, Plated, Hello Fresh, etc.) which is becoming very crowded and riddled with barriers to profitability.
Ashifi Gogo, CEO, Sproxil (No. 38)

Feels so. Is it time for… disruption?
Dhivya Surayadevera, VP of finance and treasurer, GM (No. 5)

Many people, smarter than I am, have been humbled trying to predict this.
Michael Dubin, Founder and CEO, Dollar Shave Club (No. 34)

Yes. When companies are getting funded that sell subscriptions to sustainable footstools made from Alpacas, you’ve reached the hilt.
Chris Wanstrath, CEO, GitHub (No. 31)

Yes, but it's an oversimplification to say the 90s have returned. Things are certainly frothy, and no one knows where exactly this bubble is, but we've also never seen this level of innovation before. There's so much legitimately great stuff happening.