BABA (and Walmart to a certain degree) are 21st century online retailers while AMZN is a 21st century tech giant.Agreed that they have added risk.
Where do you get the idea that BABA is an online retailer? IINM their roots are actually in B2B (and I've found suppliers in China after finding them on alibaba.com - through Google search
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AMZN is definitely a major disrupter, but there's a huge problem when 5 companies represent such a huge percentage of the overall stock market valuation.
Remember, a stock is a claim on the future earnings of a company. How much is it reasonable to pay for a year's earnings? How about if we know (do we have נבואה?) that those earnings will grow at a certain clip? I claim ignorance, I don't know what will happen, but please don't tell me that buying at crazy valuations isn't speculation. AAPL on the other hand, actually pays a dividend (I got some AAPL shares at much lower prices) is sitting on LOTS of cash, and is GENERATING lots of cash. What does the future hold? I don't know. I admire AAPL for the quality of their products, and hate their products (and the move to touchscreens that was started by them).