2025 – DUE 29 August 2025; 100% correct solutions
and explanations.
a) Volatility Dynamics in South African Equity Markets
𝑮𝒊𝒗𝒆𝒏
𝛼 = 0.07, 𝛽 = 0.91, 𝜔 = 𝛾 = 0.000015\𝑎𝑙𝑝ℎ𝑎 = 0.07,\; \𝑏𝑒𝑡𝑎 =
0.91,\; \𝑜𝑚𝑒𝑔𝑎 = \𝑔𝑎𝑚𝑚𝑎 = 0.000015𝛼 = 0.07, 𝛽 = 0.91, 𝜔 = 𝛾 =
0.000015
𝑃𝑟𝑒𝑣𝑖𝑜𝑢𝑠 𝑣𝑎𝑟𝑖𝑎𝑛𝑐𝑒: 𝜎𝑡 − 12 = 0.0012\𝑠𝑖𝑔𝑚𝑎_{𝑡 − 1}^2 = 0.0012𝜎𝑡 − 12 =
0.0012
𝑅𝑒𝑡𝑢𝑟𝑛 𝑠ℎ𝑜𝑐𝑘: 𝜀𝑡 − 1 = 0.045\𝑣𝑎𝑟𝑒𝑝𝑠𝑖𝑙𝑜𝑛_{𝑡 − 1} = 0.045𝜀𝑡 − 1 =
0.045 (𝑖. 𝑒. , 4.5%4.5\%4.5%)
𝑀𝑜𝑑𝑒𝑙: 𝜎𝑡2 = 𝜔 + 𝛼𝜀𝑡 − 12 + 𝛽𝜎𝑡 − 12\𝑠𝑖𝑔𝑚𝑎_𝑡^2 =\𝑜𝑚𝑒𝑔𝑎 +
\𝑎𝑙𝑝ℎ𝑎\𝑣𝑎𝑟𝑒𝑝𝑠𝑖𝑙𝑜𝑛_{𝑡 − 1}^2 +\𝑏𝑒𝑡𝑎\𝑠𝑖𝑔𝑚𝑎_{𝑡 − 1}^2𝜎𝑡2 = 𝜔 + 𝛼𝜀𝑡 − 12
+ 𝛽𝜎𝑡 − 12
(𝒊) 𝑪𝒐𝒏𝒅𝒊𝒕𝒊𝒐𝒏𝒂𝒍 𝒗𝒂𝒓𝒊𝒂𝒏𝒄𝒆 𝒕𝒐𝒅𝒂𝒚
1. 𝑆𝑞𝑢𝑎𝑟𝑒 𝑡ℎ𝑒 𝑠ℎ𝑜𝑐𝑘:
𝜀𝑡 − 12 = 0.0452 = 0.002025\𝑣𝑎𝑟𝑒𝑝𝑠𝑖𝑙𝑜𝑛_{𝑡 − 1}^2 = 0.045^2
= 0.002025𝜀𝑡 − 12 = 0.0452 = 0.002025
2. 𝑀𝑢𝑙𝑡𝑖𝑝𝑙𝑦 𝑏𝑦 𝛼\𝑎𝑙𝑝ℎ𝑎𝛼:
0.07 × 0.002025 = 0.000141750.07 \𝑡𝑖𝑚𝑒𝑠 0.002025
= 0.000141750.07 × 0.002025 = 0.00014175
3. 𝑀𝑢𝑙𝑡𝑖𝑝𝑙𝑦 𝑝𝑟𝑒𝑣𝑖𝑜𝑢𝑠 𝑣𝑎𝑟𝑖𝑎𝑛𝑐𝑒 𝑏𝑦 𝛽\𝑏𝑒𝑡𝑎𝛽:
0.91 × 0.0012 = 0.0010920.91 \𝑡𝑖𝑚𝑒𝑠 0.0012 = 0.0010920.91 × 0.0012
= 0.001092
4. 𝐴𝑑𝑑 𝑎𝑙𝑙 𝑝𝑎𝑟𝑡𝑠 𝑤𝑖𝑡ℎ 𝜔\𝑜𝑚𝑒𝑔𝑎𝜔:
0.000015 + 0.00014175 + 0.001092
= 0.001248750.000015 + 0.00014175 + 0.001092
= \𝑏𝑜𝑥𝑒𝑑{0.00124875}0.000015 + 0.00014175 + 0.001092
= 0.00124875