No. You are conflating "valuation" with "value". Let me give you an example.
My company has 10 shares total and I manage to get you to buy one of them for $100. The logical conclusion is that the shares are worth $100 each and the company is worth $1000. You hold 1 share, and I hold 9 shares. I also have the $100 you gave me. So one can say that you bought 10% of the company at a $1000 valuation.
But let's say I don't do anything at all with the money you gave me and I had no other money to begin with. What that means is that you have 1 share and I have 9 shares and $100. If we liquidated the company now, you would get $10 back and I would keep $90. The company has a value of $100.
Now let's say that somebody is really interested in buying shares. I give you the OK to sell your share and somebody offers to buy it for $10,000. You sell your share for $10,000 (10% of the company). The logical conclusion is that the other 9 shares are worth $90,000 and the whole company has a valuation of $100,000. But I still only have $100 in the bank :-)
Now, let's say that encouraged by the huge profit you made, you buy 4 shares at $20,000 each from me. The valuation of the company is logically $200K because there are 10 shares and the last time someone bought some it was for $20K each. You own 40% of the company. I own %50 of the company and they person who bought the original share from you owns %10 of the company. The company has $80,100 in the bank. You try to sell your 4 shares now, but nobody wants to buy. The shares have a nominal value of $8,010 each ($80,100 / 10 shares), but nobody feels like buying. Your shares are worth 0 because I control the company and don't want to liquidate. Basically, I conned you into giving me $80,100 :-)
Shares are worth what other people are willing to pay for them. Whether or not someone will be willing to buy your shares back for the current "valuation" of the company depends a lot on the circumstances. Whether you are even able to sell your shares depends on agreements you made, etc, etc. You can easily have a company with a $1 billion valuation whose stock is worth less than toilet paper in reality.
Companies that are pre-IPO are really ripe for the hype machine. You generally can't trade their stock except at a "liquidation event". You can invest in them, and their valuation might climb, but you can actually realise any of that profit. If they pull a Theranos on you, then you lose all of that money. Once a company has IPOed, the stock is traded freely on the stock market. Since it is liquid, you are more likely to be able to sell your stock close to its current valuation. Keep in mind that this is still not the same as value -- stocks usually trade a prices of multiples of the current value (because people believe the companies will increase in value over time).
My company has 10 shares total and I manage to get you to buy one of them for $100. The logical conclusion is that the shares are worth $100 each and the company is worth $1000. You hold 1 share, and I hold 9 shares. I also have the $100 you gave me. So one can say that you bought 10% of the company at a $1000 valuation.
But let's say I don't do anything at all with the money you gave me and I had no other money to begin with. What that means is that you have 1 share and I have 9 shares and $100. If we liquidated the company now, you would get $10 back and I would keep $90. The company has a value of $100.
Now let's say that somebody is really interested in buying shares. I give you the OK to sell your share and somebody offers to buy it for $10,000. You sell your share for $10,000 (10% of the company). The logical conclusion is that the other 9 shares are worth $90,000 and the whole company has a valuation of $100,000. But I still only have $100 in the bank :-)
Now, let's say that encouraged by the huge profit you made, you buy 4 shares at $20,000 each from me. The valuation of the company is logically $200K because there are 10 shares and the last time someone bought some it was for $20K each. You own 40% of the company. I own %50 of the company and they person who bought the original share from you owns %10 of the company. The company has $80,100 in the bank. You try to sell your 4 shares now, but nobody wants to buy. The shares have a nominal value of $8,010 each ($80,100 / 10 shares), but nobody feels like buying. Your shares are worth 0 because I control the company and don't want to liquidate. Basically, I conned you into giving me $80,100 :-)
Shares are worth what other people are willing to pay for them. Whether or not someone will be willing to buy your shares back for the current "valuation" of the company depends a lot on the circumstances. Whether you are even able to sell your shares depends on agreements you made, etc, etc. You can easily have a company with a $1 billion valuation whose stock is worth less than toilet paper in reality.
Companies that are pre-IPO are really ripe for the hype machine. You generally can't trade their stock except at a "liquidation event". You can invest in them, and their valuation might climb, but you can actually realise any of that profit. If they pull a Theranos on you, then you lose all of that money. Once a company has IPOed, the stock is traded freely on the stock market. Since it is liquid, you are more likely to be able to sell your stock close to its current valuation. Keep in mind that this is still not the same as value -- stocks usually trade a prices of multiples of the current value (because people believe the companies will increase in value over time).
Edit: I have trouble multiplying by 4... :-P