Step 1
Break the evaluation period into two subperiods based on timing of cash flows:
Holding period 1:
beginning price = $300.00
dividends paid = $5.00
ending price = $320.00

Holding period 2:
beginning price = $640.00 (2 shares)
dividends paid = $10.00 ($5 per share)
ending price = $660.00 (2 shares)

Step 2
Calculate the HPR for each holding period

\text{HPR}_1 = \frac{(\`$320` - \`$300` + \`$5`)}{\`$300`} = 0.0833 \text{HPR}_2 = \frac{(\`$660` - \`$640` + \`$10`)}{\`$640`} = 0.046875

Step 3
Take the geometric mean of the annual returns to find the annualized time-weighted rate of return over the measurement period.

$$(1 + \text{time-weighted rate of return})^2 = 1.0833 \times 1.046875$$ $$\text{time-weighted rate of return} = (1.0833 \times 1.046875)^{\frac{1}{2}} - 1 = 0.064931$$