Based on the historical-cost principle, under GAAP, most assets held on the balance sheet are to be recorded at the historical cost even if they have significantly changed in value over time. For example, if a company buys a plot of land or building for $50,000, then that amount appears on their company books. However, if the market value of the property increases over time to $100,000, then the asset listed is undervalued. The result is a hidden asset of $50,000. In fact, according to the GAAP the property must remain on the balance sheet with its original purchase price.
Under current standards, in most cases US accounting standards do not allow capitalization of internally generated intangible assets and costs associated with their research and development are expensed during the current period. For example, if a company has applied for a patent, this may have a certain value by allowing products to be manufactured and sold. The patent could also be sold but the company does not have to include its assumed value in the balance sheet. As a result, the balance sheet value of the company is lower than its actual value. A hidden reserve has been created.