Options Open Interest Question

When looking at a vertical spread on Tastyworks it showed huge open interest. I then looked at the exact same option on Thinkorswim and it showed very little open interest. Why would that be? Is that measurement specific to the trading platform?

All platforms are buying from the same available pool of options correct?

Point is, should I be concerned about being able to sell an option that I buy through say TOS because the open interest is lower? Or open interest is open interest across all platforms?

Thanks

 

OI is based on the OCC End of day values. Not broker or platform dependent. Also, IMO, OI on one strike is not an important metric. As long as the base symbol has a lot of OI and action, the strikes will be liquid and so will the spreads. Only MMs see your orders (in general).

 

Thanks so how does that explain the huge discrepancy between the two? Shouldn’t they both get the same end of day values?

 

If they updated their values at the same time, yes. What option?

 

Please, details?

Firstly, how do you look at open interest for a vertical spread? I guess by combining the individual strikes?

You should view open interest by single-strikes.

Secondly, tastyworks and TOS are trading software platforms. They should have the same data (open interest) for any given security.

If you can give a specific example, we might be able to help.

 

Here is a picture of AAPL YOu can see they match on both Lightspeed and Silexx.

 

Thanks for the information everyone. I figured it out. I was comparing spreads to single calls. When I changed to single calls it all lines up. I’m a noob so stupid error on my part. Thanks for your time.

 

we all were noobs at one point. Keep learning and keep asking questions!