HP (NYSE: HPQ US) shares are rallying on Wednesday, after the computer hardware company reported fourth-quarter results that are seen as strong, supported by positive demand and pricing in the personal computer market. Revenue gained 9% to $16.7 billion in the fourth quarter. Analysts, on average, projected $15.4 billion. While the company is getting a boost from higher demand, HP has struggled to fill all its orders because of shortages of some types of chips.