Probably not. Your employee stock agreement probably requires company approval for transfers, and unless you're at a large company that already has a liquid market for its equity, that approval will not be granted.

Have provisions like that been held up in court? It seems to go against the strong stockholder laws in Delaware. Not being able to sell your shares is probably the most important right there is.

Yes. Control and transferability restrictions are basic corporate governance.

We're talking about private companies, not public ones. Easy liquidity is not an important feature of closely-held private company stock.

Before you exercise, make sure you are familiar with the Alternative Minimal Tax and how exercising Stock Options affect it. See https://www.wework.com/magazine/knowledge/startup-equity-und... and https://gigaom.com/2011/06/05/5-mistakes-you-cant-afford-to-... (especially the David Weekly at the bottom). Some people went bankrupt for that. Also check the rules on ISO (I supposed you have ISO options).

Then I think the best you can do is to sell the right to own the stocks when you will be able to sell them according to your stock plan. In practice you cannot sell the stock now but you can have a contract with a person that you will sell them as soon as you can. Or something like that...

On how to find somebody willing to buy them, I am not sure. Common stocks are considered almost worthless by a lot of investors. There are also some information about preference in round of funding etc, that a sophisticated investor would like to know but it is not always public knowledge outside of the board.

Before Facebook IPO I know SecondMarket was the place. I am actually curious about the options here.

Consider talking to the company about it. If they're doing well, (and aren't concerned you might leave) they might be interested in buying the options back.

Read your purchase agreement, employment contract, articles of incorporation, buy/sell agreement etc. It is common for the circumstances for the transfer of shares to be established to handle this sort of situation because founders don't want just anyone owning shares. If something is unclear, consult an attorney.

One common way of handling these situations is for the founders or the company or other employees to purchase the shares. A loan with the shares as collateral is another possibility.

Keep in mind that selling shares may be viewed as a lack of faith in the company [likewise if the founders are not interested in reacquiring your shares.

Good luck.

If the company is doing well enough that outside parties would be interested in getting in in such an unusual way maybe it is time to ask for a raise?

While you likely can't transfer ownership of your shares, you can take a loan out on the sell value of those shares at some predetermined later date. The legalities are somewhat sticky, but it is possible.