I wrote a script to track adjusted vs. unadjusted prices for Apple using pipeline vs. the vanilla API.
In the output, you can see the adjusted price in olive green, and the unadjusted price in purple. I'm confused by why the unadjusted price drops down to the level of the adjusted price in mid-2014: shouldn't the adjusted price keep rising (into the 700s)? Did I make a mistake in my implementation, or is there an error in the adjusted price data?
It looks like the adjusted and unadjusted labels are backwards! The big drop that you see in 2014 is the 7:1 split that occurred with AAPL. Since you're only looking back one day at a time in Pipeline, you are printing the pricing data for AAPL as of the point in time that it's called which is unadjusted. If your window was multiple days, everything in that window would be split adjusted as of the date which it is called in the simulation.
Everything in data is split adjusted in backtesting as of today's date (not the date in the simulation).
Check out this post for more details on the issue.
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The material on this website is provided for informational purposes only and does not constitute an offer to sell, a solicitation to buy, or a recommendation or endorsement for any security or strategy, nor does it constitute an offer to provide investment advisory services by Quantopian.
In addition, the material offers no opinion with respect to the suitability of any security or specific investment. No information contained herein should be regarded as a suggestion to engage in or refrain from any investment-related course of action as none of Quantopian nor any of its affiliates is undertaking to provide investment advice, act as an adviser to any plan or entity subject to the Employee Retirement Income Security Act of 1974, as amended, individual retirement account or individual retirement annuity, or give advice in a fiduciary capacity with respect to the materials presented herein. If you are an individual retirement or other investor, contact your financial advisor or other fiduciary unrelated to Quantopian about whether any given investment idea, strategy, product or service described herein may be appropriate for your circumstances. All investments involve risk, including loss of principal. Quantopian makes no guarantees as to the accuracy or completeness of the views expressed in the website. The views are subject to change, and may have become unreliable for various reasons, including changes in market conditions or economic circumstances.
