Quick answer: JP Morgan (NYSE:JPM) analysts upgraded ratings on Seagate (NASDAQ:STX) based on HDD unit trends that appear to have bottomed and favorable pricing. The price target was raised to $23 from $16. The firm also upgraded Western Digital (NYSE:WDC) to Overweight from Neutral.
Also contributing to the run on data storage stocks today is news that OCZ Technology Group (NASDAQ:OCZ) topped analyst expectations in its FQ1 earnings, leading the stock up over 12.5% in trading. These stocks are trading higher on the good news:
STEC Inc. (NASDAQ:STEC) up 7.78%, Western Digital Corp. (NYSE:WDC) up 2.65%, SanDisk Corp. (NASDAQ:SNDK) up 1.19%, Seagate Technology (NASDAQ:STX) up 2.76%, EMC Corp. (NYSE:EMC) up .97%, Hutchinson Technology (NASDAQ:HTCH) up 1.16%, and Dataram Corp. (NASDAQ:DRAM) up 2.64%.