Platform that runs scripts monitoring stock market activity? Possibly executes trades?
Are there any software platforms out there that can be used to run scripts that monitor stock market activity?
I would like to write a script to send myself alerts when certain market conditions occur. Ideally it would also have the ability to execute trades.
I'm not looking for anything super complicated and I do not need expensive real time data. I'm looking to do simple stuff like:
If "SDY" drops to 5% below the DOD, then sell 50% of "DOD" to buy SDY
Edit
Looks like ETrade Offers an API. Not as simple as I'd like ideally, but here is is for anyone else who is interested in this question: https://us.etrade.com/e/t/activetrading/api
Answer
From what I've seen, Tradelink does it all and supports multiple bourses, though it might be what you'd consider super-complicated. Possibly their most active API is for Interactive Brokers.
Other solutions appear to be brokerage-specific or not free.
For TD Ameritrade you might like their free StrategyDesk win32 downloadable; its simple trade automation is awesome. I don't even remember how I stumbled upon it since it's pretty well hidden or unadvertised in favor of their more modern platforms (all of which seem to lack trade automation though).
Even more defunct but equally useful might be Trade-Ideas, able to trade stocks based on rules and technical-analysis signals. It runs as a module of the ancient QuoteTracker or even stand-alone. In demo mode the signals are shown with 20min delay, but you can still place orders based on them in realtime...sweet! They support TD Ameritrade accounts and maybe also Scottrade, since ScottradeELITE software bundles in their Trade-Ideas module.
On the fringes, OptionsXpress has Xecute which basically links your account to a choice of investment advisory services to manage your portfolio for you, for a monthly fee.
Both OptionsXpress and TD Ameritrade offer developer API's which I've used, but still found their websites to be more feature-rich. So like with Scottrade I've actually written my own programs to drive their websites (nowadays using Ruby libraries Mechanize and Watir-Webdriver/Selenium) and perform live trades based on analysis and rules like yours my other programs prepare earlier.