Category	Low	High

Long-term bond rate	3.9%	4.4%
Equity market risk premium	4.6%	5.6%
Adjusted beta	1.31	2.1

Additional risk adjustments	0.0%	0.5%
Cost of equity	9.9%	16.6%

Tax rate	6.2%	6.7%
Debt/Equity ratio	1	1
Cost of debt	5.0%	5.0%

After-tax WACC	7.3%	10.6%


Selected WACC	9.0%

POWI WACC - Detailed calculations of Beta

		Debt/Equity		Unlevered
Peers	Company Name	ratio	Beta	beta

POWI	Power Integrations Inc	0.88	1.48	0.81
ASTI	Ascent Solar Technologies Inc	0.01	0.57	0.57
DIOD	Diodes Inc	0.02	1.8	1.77
IPHI	Inphi Corp	0.05	0.93	0.89
JKS	JinkoSolar Holding Co Ltd	8.34	0.7	0.08
MAXN	Maxeon Solar Technologies Ltd	7.22	0.29	0.04
MTSI	MACOM Technology Solutions Holdings Inc	0.05	1.85	1.76
PI	Impinj Inc	0.08	1.98	1.85
PTK.V	POET Technologies Inc	0	0.3	0.3
SPWR	SunPower Corp	0.45	1.82	1.29
SYNA	Synaptics Inc	0.38	2.01	1.48

	Low	High

Unlevered beta	0.81	1.29
Relevered beta	1.46	2.64
Adjusted relevered beta	1.31	2.1

POWI's CAPM model and how its cost of Equity is calculated

The Cost of Equity reflects the return a company needs to deliver to shareholders to justify the risk of investing in its shares. It’s computed using the Capital Asset Pricing Model (CAPM), which blends the risk-free rate, the stock’s beta, and the market risk premium.

This method evaluates the stock’s risk compared to a safe investment and the market’s overall volatility.

Here’s how we figure out the cost of equity for POWI:

cost_of_equity (13.25%) = risk_free_rate (4.15%) + equity_risk_premium (5.10%) * adjusted_beta (1.31) + risk_adjustments (0.25%)

We include the risk adjustments, which range from 0% to 1%, to keep our WACC conservatives, especially for companies traded in developing markets.