The curse of same-day changes

I find it fascinating when something has a default design, and you are positively surprised by a product that has thought about this design and improved it. Over the last few months, I've been looking at stocks. And I noticed that there's a bad, bad default in the standard chart: Same-day changes:

• Why is this bad? Trading based on day-to-day changes is a great way to lose money. Then why is it shown by default? Maybe because it maximizes engagement, but maybe also because other sites are doing it?
• If I change the period to something more informative, say a week, then the app will forget this when I next use it! In addition to defaulting to daily, the apps do not learn that this default is wrong for me!

See an example from the iPhone Stocks app, and this looks similar for many web apps that I've checked in addition (e.g. Google or Yahoo Stocks):

One day is not the right time period for me, because I invested one week ago. So I switch to the weekly display, and: It does not tell me what's important for me! The graph adjusts, and I know I lost money, but I don't know how much!

Here's how Robinhood does it better by displaying this information:

This might seem small, but to me this, in itself, is a reason to use Robinhood. They have thought about what information I need, and they are giving that to me. Thank you!

Can we do better?

Some ideas for tweaking these graphs:

• Below this chart, Robinhood also shows the "open" and "close" (thus giving me daily changes). Why not adjust all those values to the relevant period, and thus talk about "initial", "latest", and "max"?
• A loss is red, a gain is green. That makes sense. But how about the magnitude? A 0.02% loss is shown with the same color as a 20% loss? A simple solution here would be to introduce shades of red and green. This is especially noticeable in graphs comparing different stocks.
• Can we explain movements in the stock price? Or at least give some context in cases where it's obvious why a movement occurred? For instance, we could add vertical lines at the time that an earnings report comes out. If we are being very fancy, then use machine learning to link changes in stocks to news, so that I understand what drove the change. This feels especially useful for a product like Robinhood, where they could say "We help you really understand stocks"