I would check out sharespost, equityzen, or equidate (and also search for them on Hacker News, as I found others mention experience with sharespost). I don't have direct experience, but I was helping a friend with a number of shares in a late stage startup research the sell side, and those are the companies that came up.
It crossed my mind to buy shares but I haven't done so. For some of them, you have to be an accredited investor, which means a certain net worth/income threshold to be met. (I think the SEC is trying to prevent naive investors from getting fleeced in this "dark" market). SharesPost seems to have a fund that gets you exposure to a lot of late stage startups.
AngelList apparently has a fund for early stage startups... if anyone knows anything about that I would appreciate any feedback.
EDIT with more info: From my research, buying from every company is different. That is why companies like SharesPost exist. And you really should have the permission of the company to do the transaction.
I think it may be possible to do it without their permission, but that's beyond my knowledge. There should be employees willing to go through this effort because they stand to benefit because you are offsetting their tax risk.
I don't know since I haven't used them yet. I imagine the middleman is fairly well aligned with you because their business model is to take a cut of the transaction. If they're getting 5% of a $100K or $500K transaction, that's a fairly good incentive not to try to screw people over. Disputes cost time and money.
The party that isn't aligned is the employer. As mentioned, they hold right of first refusal, and they may balk at having "strangers" on the cap table.
I'm sure there is a whole bunch of "interesting" paperwork and if you had a lawyer look at it they would gladly take your money. I believe each company is different, because the way you hold private shares depends on the company governance. SharesPost has presumably done some of the legwork for you because they are advertising this facilitation only for specific companies, which they have hopefully vetted in some way.
I imagine that SharesPost exists precisely because people had to get lawyers and accountants involved to do these custom transactions, and now they are pushing it to the lower end of the market. But they are also fairly new so they can't be perfect.
It crossed my mind to buy shares but I haven't done so. For some of them, you have to be an accredited investor, which means a certain net worth/income threshold to be met. (I think the SEC is trying to prevent naive investors from getting fleeced in this "dark" market). SharesPost seems to have a fund that gets you exposure to a lot of late stage startups.
AngelList apparently has a fund for early stage startups... if anyone knows anything about that I would appreciate any feedback.
EDIT with more info: From my research, buying from every company is different. That is why companies like SharesPost exist. And you really should have the permission of the company to do the transaction.
I think it may be possible to do it without their permission, but that's beyond my knowledge. There should be employees willing to go through this effort because they stand to benefit because you are offsetting their tax risk.