If a firm just paid a dividend equal to $4.00 a share, then for the WACC, in order to find the cost of equity, $4 should be

To find the cost of equity for a firm, the dividend per share can be used as one component. However, it is necessary to consider a few other factors as well.

The cost of equity represents the return required by the firm's shareholders or investors. It is calculated using the dividend growth model, which incorporates the dividend per share, the expected dividend growth rate, and the required rate of return.

Here's how you can calculate the cost of equity using the dividend growth model:

1. Determine the dividend per share (DPS): In this case, the dividend per share is given as $4.00.

2. Determine the expected dividend growth rate (g): The expected dividend growth rate is an assumption about the future growth of dividends. This can be estimated based on historical dividend growth rates, industry averages, or company forecasts.

3. Determine the required rate of return (r): The required rate of return is the minimum return expected by investors for investing in the company's equity. This rate can be estimated using various models, such as the Capital Asset Pricing Model (CAPM), or it can be based on other factors like industry benchmarks.

Once you have estimated the dividend growth rate and the required rate of return, you can use the dividend growth model to calculate the cost of equity:

Cost of Equity (Ke) = DPS / Price + g

Where:
- DPS is the dividend per share
- Price is the current market price per share
- g is the expected dividend growth rate

It's important to note that the cost of equity is just one component used in calculating the Weighted Average Cost of Capital (WACC). The WACC represents the average cost of all the sources of financing (equity and debt) for a firm. Therefore, you will need additional information on the firm's debt financing, interest rates, and weights of each component to calculate the WACC accurately.