Programming Snapshot – Terminal Stock Portfolio

According to US Vice President Kamala Harris, most US citizens would run out of money if faced by only $400 of unexpected costs. Since hearing this, I have made it my job to check every day whether I still have sufficient financial reserves. This includes tracking the current share price performance of some well-known companies. While there are many apps with portfolio settings that monitor a number of selected shares, I prefer to use command-line tools written in Go that run in a terminal window.

Figure 1 shows the output of the Go Pofo program (Pofo stands for portfolio). The Pofo program's output displays in six tiles (three at the bottom and three at the top), with each tile containing a bar chart to illustrate the share price performance of Apple, Netflix, Meta, Amazon, Tesla, and Google over the past six weeks. The program grabs the current and historical share price data from the data dealer Twelve Data [1] in a fraction of a second shortly after launching. Twelve Data offers a free basic plan for hobbyists that allows up to eight requests per minute and up to 800 per day before a limit kicks in.

The program fetches the closing prices in US dollars of the six monitored shares on the New York Stock Exchange for the past 45 business days. It does so in one fell swoop with a single request to the server. Figure 2 shows the data for the hyper-nervous Netflix stock in the period between June 16 and July 31, 2023. In this time frame, the value of the share fluctuated wildly between $413.17 and $477.59. Alas, in a graph of absolute values, it is still more or less impossible to see any fluctuations, because, after all, the difference only accounts for around 15 percent of the total value.

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