A minority investor company can hold material influence over the investee company and this commonly occurs at the 20% to 50% voting rights ownership level.
Significant Influence Indicators: Example indicators of significant influence are: investor seats on the board of the investee, sharing of management by investor and investee, or a shared technology dependency between investor and investee.
Equity Method for Minority Active Investment Reporting on Investor Company Balance Sheet (GAAP & IFRS).

Investment Cost in Excess of the Investee’s Book Value
BV of Investee = BV of Total Assets – BV of Total Liabilities
Commonly when a company makes a minority active investment, the price paid exceeds the proportional book value of its stake in the investee. For example, an investor company may pay 60% of the book value to acquire a 50% stake in another company.
The equity method has a two-step approach for reconciling the difference between the book value of the equity investment and the cost of the investment, where book value = bv of assets – bv of liabilities.

Impairment and the Equity Method
A minority active investor company’s equity investments must be tested for impairment.
Example: Assume that a large pharmaceutical company has made an investment in a small laboratory. The laboratory is focused on the development of a single drug. In the event that this drug fails its approval tests by government regulators shortly after the investor company reports its financial statements to the public, then the balance sheet value of the large pharmaceutical company’s stake in the small lab is likely to have declined.
Impairment: When the fair value of the equity investment falls permanently below its carrying value on the investor’s balance sheet, then an impairment loss must be recognized on the investor’s income statement and the value of the investment on the balance sheet is reduced to its fair value.
US GAAP & Impairment: reversal of impairment losses is not allowed.
IFRS & Impairment: reversal of impairment losses is allowed.