Sandisk stock is up 7.2% through 9:50 a.m. The companies say their 9th-generation flash chips both read and write data 33% faster than the previous 8th-generation chips and are more power-efficient. Valued at $181 billion today, Sandisk's stock price has come down a lot since closing at a record $2,335 in late June. But at this price, just maintaining its current position in the memory market should be enough to make Sandisk stock a winner. Before you buy stock in Sandisk, consider this:The Motley Fool Stock Advisor analyst team just identified what they believe are the 10 best stocks for investors to buy now… and Sandisk wasn't one of them.