Securities Act of 1933: Federal law governing initial public offerings and securities registration requirements, including private placement exemptions relevant to private company stock sales.

Securities Exchange Act of 1934: Federal law regulating secondary market trading, including requirements for securities transfers and anti-fraud provisions.

Rule 144: SEC rule providing a safe harbor for private resales of securities, particularly important for restricted stock transfer provisions.

Regulation D: SEC regulations providing exemptions for private placement offerings, crucial for private company stock sales.

Blue Sky Laws: State-specific securities laws governing registration, disclosure requirements, and exemptions for stock sales within each state.

State Corporation Laws: Laws governing corporate formation, operation, and stock issuance in the state of incorporation (e.g., Delaware General Corporation Law).

Internal Revenue Code: Federal tax laws affecting stock transfers, capital gains, and related tax implications of stock purchases.

ERISA: Employee Retirement Income Security Act governing employee benefit plans and relevant when stock purchases involve employee equity.

SEC Rule 701: Exemption for companies offering securities as part of employee compensation plans.

Hart-Scott-Rodino Act: Antitrust law requiring notification and review of large stock acquisitions that may impact market competition.

CFIUS Regulations: Regulations governing review of foreign investments in US companies for national security implications.

State Contract Laws: General contract law principles and requirements governing formation and enforcement of stock purchase agreements.

Uniform Commercial Code: Standardized commercial laws adopted by states governing commercial transactions, including Article 8 relating to investment securities.