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Bad price data or bad understanding of historic pricing?

Hi guys,

I'm really puzzled about the pricing I'm seeing for symbols like TMF, TQQQ. These are etf's that should not be affected by stock splits,
yet their pricing varies significantly (by 50% -70%) of the results I see in charting packages like Yahoo or Stockcharts.

Look at the following, which maps the effect of owning 100% of TMF versus the default of SPY, and records the prices of TMF below it. In July 2016, TMF suffered badly according to stockcharts , dropping from a high of about $31.58 to a low of around $16.24. But that's nothing compared to what Quantopian data records: Q shows these prices to drop from $121.05 to lows of $17.04. So they both end up at around the same price but the starting number diverges drastically.

Can anybody explain this to me?


Clone Algorithm
Backtest from to with initial capital
Total Returns
Max Drawdown
Benchmark Returns
Returns 1 Month 3 Month 6 Month 12 Month
Alpha 1 Month 3 Month 6 Month 12 Month
Beta 1 Month 3 Month 6 Month 12 Month
Sharpe 1 Month 3 Month 6 Month 12 Month
Sortino 1 Month 3 Month 6 Month 12 Month
Volatility 1 Month 3 Month 6 Month 12 Month
Max Drawdown 1 Month 3 Month 6 Month 12 Month
# Backtest ID: 59164a0e4a16f3619f25a6bf
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2 responses

It looks like TMF and TQQQ each had splits, which is causing the differences that you see.


The prices will be split when you make historical lookbacks after each split, but logging the current price will show the prices that were known as of the simulation date.


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Thanks for that. All makes sense to me now.