Apple’s stock is under pressure as investors grapple with the impact of sharply rising memory chip prices on the company’s profitability. The iPhone giant’s upcoming earnings report, due after market close on Thursday, should offer the first clear insights into the extent of the issue. The stock has just wrapped up its eighth straight weekly loss, a streak not surpassed since 1993. Memory prices are projected to remain elevated for the foreseeable future amid brisk demand. Memory represents between 10% and 20% of the cost of building a smartphone, according to technology research firm IDC, which called the rise in memory prices a “crisis” for hardware companies.