Netscape Communications Corp’s shares shot up 24% yesterday through combination of factors, although the appointment of a chief operating office was not thought to be the most important. The company announced Barry Ariko as executive vice president and COO. Ariko was previously head of Oracle Corp’s sales operations in the Americas. However, the Street got more excited due to the lack of an earnings warning for once. Netscape’s fiscal now ends October 31, so if it had bad news about its third quarter, we would have heard about by now, so the thinking goes. The earnings are due next Tuesday, August 18. Also driving them skywards were rumors that Citicorp, already a prominent customer of the internet software company, would be choosing Netcenter as its primary portal for its financial services. Netscape closed up $6.125, or 24.4% at $31.1875 on more than triple its average daily volume.