Apple (AAPL 0.55%) stock has taken a beating this year, with its shares down by 19% as of this writing. It might be tempting to attribute that performance to marketwide troubles, and that's partly true. However, even as the Nasdaq Composite has recovered from being in bear market territory some weeks ago -- and is now slightly in the green for the year -- Apple has trailed far behind. The most immediate problem for the tech leader is President Trump's trade agenda, but there are others, including the fact t ...