In the spring of 2015, my club, Humans vs. Zombies, ran a 5-day game where corporations played a large part in the plot and the market for boosts and debuffs. To get ready, I wrote this stock market and banking system in Google Sheets that would allow people to deposit and withdraw their "money" and buy and sell stocks in a small stock market. Ultimately, I made the buying and selling too strong of a mechanic, and as you can see in the graph included in the sheet, many players figured out a way to game the system. Transactions were entered in "All Transactions" while bank accounts were tracked in "Messy-Players" and stock values were calculated in "Messy-Stocks."

There were two other files that players could view that gave them the current stock prices and the players' portfolios. They are shown in the linked google sheets folder, but are analogous to the "Master Players" and "Buffs and Debuffs" pages. The folder can be reached here: https://drive.google.com/open?id=1qlsHLqgJVKzzEslxsF3F2zwjHxhcB_P--gpnRLia-UU