I have a bunch of stocks and mutual funds in my portfolio. I’d like to sell some small percent of these “traditional” investments and purchase some cryptocurrency. But I’m trying to figure out how to calculate when is the best time to do this transfer.

Basically, what I want is to see some chart and setup an alert that tells me:

1. When the stock price is high (relative to my fiat currency) and
2. When the price of the cryptocurrency is low (relative to the above fiat currency)

First, how do I do this theoretically? Is there some way to construct a chart that simplifies two lines into one line, which is some calculation of the two lines that shows a single line with points very high on the y-axis when the above two conditions are true, and very low on the y-axis when the above conditions are not true?

Second, how can I setup an alert that tells me when the chart above is at some sort of year-time-high, so I can be alerted that “now” is a good time to sell stocks and buy the given cryptocurrency.