Are you a savvy Trader? Can you take a small amount of gold and turn it into a pile of cash? Investment will give you the chance! Buy stocks from any of the four Companies and sell at a high price! (This is a beta version and is completely done via SMAPI console. A graphic interface is in the work, but the mod is fully functional without it!)
Installation:

Download and Install SMAPI
Download this Mod
Unzip and place Investment Folder in your Mods Folder

How Does it Work?

At the start of a new game you will have no shares. You can use the console command stockprices to see the four available companies and the current stock price.

Queen of Sauce Inc - Base price 50g, rock bottom price 25g, max price 800g, interest 3%
Stardrop INC - Base price 100g, rock bottom price 50g, max price 250g, interest 5%
JojaCorp - Base price 250g, rock bottom price 200g, max price 500g, interest %7
Bank of Ferngill - Base price 1000g, rock bottom price 500g, max price 3000g, interest 15%

Each day, the prices of all the stocks will fluctuate in price either increasing or decreasing by 2g. There is a slight chance for a stock price to increase or decrease sharply (15g).
To purchase stock you must use the buystock console command buy (ex: buystock joja 1) you can buy joja, stardrop, sauce, or ferngill. If you have enough money, it will be taken from you and the amount of stock will be added to your save data. You can use stockprice to see how many of each stock you have.

To sell your stocks, simply use the sellstock command in a similar way you bought them (ex: sellstock joja 1). This will sell the amount of stock you want at the current price for the day.

Every Day 1 of each season, your interest will be calculated by each stock type you own and will automatically be added to your gold amount. The more stocks you hold, the more money you make at the beginning of the season.

Reminder: This is a beta version, there may be bugs! Report them immediately and include a SMAPI Log!!!

[/size]This Mod is Open-Source! If you have the know-how, you can improve the mod by visiting my Git Hub!