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Difference between Bloomberg data and Quantopian for SPY

I've been working on an algo and in testing noticed that Bloomberg (I have access to a terminal) gives different last price values than Quantopian.

For example on 1/2/2008 for SPY
Bloomberg = 144.93
Quantopian = 144.55

Any idea what might be going on here?

Thanks,
Cody

2 responses

A few more recent examples for SPY.

2/28/14
Bloomberg = 186.29
Quantopian = 186.33

3/3/14
Bloomberg = 184.98
Quantopian = 184.93

3/4/14
Bloomberg = 187.58
Quantopian = 187.69

These are small differences, but when I back test my strategy that I have ported from Excel which uses Bloomberg data, I get different trading signals on occasion. I would really like to live trade the system with Quantopian rather than my current manual process, but the different prices make me hesitant.

I'm pretty sure this is the post that covered this ..... https://www.quantopian.com/posts/problems-with-data-feeds-prices