credit saison co shares rose sharply monday morning following news that activist investor city index eleventh took a 51 stake in the japanese credit card company the shares were recently 17 higher at 1566 yen 1238 after rising as much as 22 earlier tokyobased investor city index eleventh said friday in a regulatory filing after market close that it has built a 51 stake after acquiring shares in the market in recent weeks city index eleventh said in the filing that it would advise management and make important proposals when necessary city index eleventh holds stakes in many different companies in finance energy construction and other industries earlier this month the investor and its associate took a 58 stake in japanese energy company cosmo energy holdings co