Investors have valid reasons to be nervous heading into Apple Inc. AAPL's earnings report after Tuesday's market close. For starters, there's the possibility a key update to the upcoming iPhone 8 release will result in a "sell the news" reaction, Robert Cihra of Guggenheim Securities said during CNBC's "Squawk Alley" segment. While this is a possibility, the analyst expects a different outcome in which Apple will generate a lot of "excitement" for the iPhone with many compelling and new features.What goes to the chart, there is a clear breakout of the rising linear channel. Stochastics are getting closer to the overbought territory. All these give more downside potential. Probably down to 147.2711. $AAPL, Apple Inc. / H1