TEPCO’s (Tokyo Electric Power Co Holdings) Stock Behaviour in the Long Run

Noting the huge impact of the Fukushima accident on TEPCO's (Tokyo Electric Power Co Holdings) activity and stock price, this study investigates the long-run patterns of returns and volatility of its stock, relative to the main return and volatility features of the Nikkei 225 over the past 30 years. The best fitting volatility for both series comes from an asymmetric power GARCH model; the standard deviation of volatility does not depend primarily on large innovations. For the Nikkei, large negative changes are not more clustered than positive changes. A regime-switching correlation model with three states reveals that a high correlation regime is the most frequent for TEPCO, with low switching probability, whereas the regime associated with the Fukushima crisis is less persistent. A strong interaction arises between the less common regimes, but the stable, low volatility regime appears mostly independent. In two regimes, the Nikkei returns have significant and negative effects on TEPCO returns, but the reverse is not true. The Fukushima environmental and industrial crisis thus could spark a new energetic era in Japan, including a real transition toward more environmentally friendly electric power.