Excellent site for backtesting equity trading strategies Excellent site for testing stock and ETF trading strategies. P123 provides a thorough point-in-time database with a powerful and flexible engine to simulate backtests of systems. And they integrate with Interactive Brokers to automate applying those strategies to live trading.

Fantastic product for individual investors If you like data driven investing and are willing to do the work, Portfolo123 provides all the information you need to construct and trade investment strategies. I've been a client for about 10 years and, for fundamental investing, I haven't found any site that comes close. You can write your own formulas to interpret the data, weight stocks in your portfolio, use your own buy and sell rules, trade weekly, monthly, or however often you think appropriate. You can test your strategies on data going back many years, and they provide articles and a forum for exchange of information to help you learn about factor investing and how to use their site. I wouldn't go anywhere else to manage my money.

Great Tool Great Tool, great team, great support. I am a very satisfied user for 9 years. I have spent countless hours on it. Only concern: their are dependent on data providers policies. It may occasionally result in changing data or pricing. Backtest servers are much faster and more reliable than in 2 other similar platforms I have tried.

Toxic environment Toxic environment that stigmatizes creative, productive, diverse critiques as so-called "unconstructive" and "repetitive" and condones toxic personal attacks.

Very flexible stock screening and backtesting platform This is the best and most flexible platform for stock and ETF screening, ranking and backtesting I know. With main focus on fundamentals, you can test, combine and vary hundreds of parameters. No programming knowledge required. One restriction: Portfolio123 does not support intraday trading.