Which of the following is NOT a legal or regulatory aspect of insurance companies?

Market share requirements are not typically considered a legal or regulatory aspect of insurance companies. Instead, the other options relate directly to the regulatory framework governing insurance operations.

Eligible investments pertain to the specific types of assets that insurance companies are permitted to hold, ensuring that they maintain adequate liquidity and risk profiles to meet their obligations to policyholders. Authorities set regulations around these investments to protect consumers and maintain the stability of the insurance market.

The prudent investor rule mandates that investment decisions made by the insurance company must be conducted with care, skill, and diligence, which is in line with a fiduciary duty to policyholders. This rule helps to ensure that the company's investments are made in a responsible manner that considers both risk and return.

Valuation methods relate to how insurance companies assess their assets and liabilities for reporting purposes, ensuring that they provide accurate and truthful financial representations. Proper valuation practices are critical for maintaining solvency and fulfilling contract obligations to policyholders.

In contrast, market share requirements—while they can influence competition within the insurance industry—are not standard regulatory conditions applied to insurance companies as part of their legal framework. Such requirements, if they exist, would be more related to antitrust issues rather than the legal and regulatory aspects of insurance operations more broadly.