I only know of a handful of prenups that didn't work, and in every case where the prenup was pierced, it was due to one of the parties not satisfying the conditions required for a valid prenup.
The number one failure? Not properly disclosing premarital assets. Disclose everything, and let the lawyer decide if it's immaterial (and as a side benefit, if they strike something from disclosure which is later found to be material in a divorce proceeding that results in the prenup being pierced, then generally your lawyer's malpractice insurance will make you whole).
How should stock be disclosed? If it's publicly traded, you disclose the stock, type of shares, stock owned, and value at the time the disclosure was compiled. If it's not publicly traded, you list the type of stock restrictions on trading/owning if any, and estimated valuation based on the most recent one conducted by the company. If you're a C-suite officer of a VC-funded company, you generally also need to get an updated valuation, and if the company won't do one you may need a third-party valuation. (If you're not an executive, or it's a privately-owned traditionally financed company, no additional valuation needed.)
The number one failure? Not properly disclosing premarital assets. Disclose everything, and let the lawyer decide if it's immaterial (and as a side benefit, if they strike something from disclosure which is later found to be material in a divorce proceeding that results in the prenup being pierced, then generally your lawyer's malpractice insurance will make you whole).
How should stock be disclosed? If it's publicly traded, you disclose the stock, type of shares, stock owned, and value at the time the disclosure was compiled. If it's not publicly traded, you list the type of stock restrictions on trading/owning if any, and estimated valuation based on the most recent one conducted by the company. If you're a C-suite officer of a VC-funded company, you generally also need to get an updated valuation, and if the company won't do one you may need a third-party valuation. (If you're not an executive, or it's a privately-owned traditionally financed company, no additional valuation needed.)