user63987: I noticed that there is a difference in the appearance of the order books among different exchanges. 
On GDAX, the USD spread is kept very low most of the time ($0.01). At these times, the buy and sell orders closest to the mid market price amount to a higher BTC value than what is actually traded.
This inherently leads to a trade history that is much more stable on a short time scale, which makes me think that it has something to with "manipulation" of the current BTC price, for example by use of bots.
Other exchanges usually have a much higher USD spread (in the order of dollars), and thus a trade history which is less stable over short periods of time. 
GDAX screenshot
(USD spread $0.01)

Bitstamp screenshot
(USD spread $12.11)

What is the reason for this discrepancy? What is the gain of forcing a more stable short-term BTC price?
Edit: Another screen shot from a moment ago. This is kind of ridiculous. Bots gone awry?


user76346: That's how market making works. GDAX has 0% for them, so is very attractive for liquidity providers.
I'm trying to be one of them, and I don't really care where the market is, as long as I can get rid of a certain position. That will make me offer prices on top of the book. If you grab a bunch of people like me, competing for that top of the book, what you get is a small spread.
Hope that clarifies things.

user15715: GDAX offers 0% fee to maker (traders who's trades are being matched by a seller or buyer). That incentives traders to try to match bid and ask as close as possible thus reducing spreads.

63987: <p>I noticed that there is a difference in the appearance of the order books among different exchanges. </p>

<p>On GDAX, the USD spread is kept very low most of the time ($0.01). At these times, the buy and sell orders closest to the mid market price amount to a higher BTC value than what is actually traded.</p>

<p>This inherently leads to a trade history that is much more stable on a short time scale, which makes me think that it has something to with "manipulation" of the current BTC price, for example by use of bots.</p>

<p>Other exchanges usually have a much higher USD spread (in the order of dollars), and thus a trade history which is less stable over short periods of time. </p>

<p><strong>GDAX screenshot</strong></p>

<p>(USD spread $0.01)</p>

<p><a href="https://i.stack.imgur.com/iXD8q.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/iXD8q.png" alt="enter image description here"></a></p>

<p><strong>Bitstamp screenshot</strong></p>

<p>(USD spread $12.11)</p>

<p><a href="https://i.stack.imgur.com/4yFwO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4yFwO.png" alt="enter image description here"></a></p>

<p>What is the reason for this discrepancy? What is the gain of forcing a more stable short-term BTC price?</p>

<p>Edit: Another screen shot from a moment ago. This is kind of ridiculous. Bots gone awry?</p>

<p><img src="https://i.stack.imgur.com/mk3RQ.jpg" alt="enter image description here"></p>
 76346: <p>That's how market making works. GDAX has 0% for them, so is very attractive for liquidity providers.
I'm trying to be one of them, and I don't really care where the market is, as long as I can get rid of a certain position. That will make me offer prices on top of the book. If you grab a bunch of people like me, competing for that top of the book, what you get is a small spread.</p>

<p>Hope that clarifies things.</p>
 15715: <p>GDAX offers 0% fee to maker (traders who's trades are being matched by a seller or buyer). That incentives traders to try to match bid and ask as close as possible thus reducing spreads.</p>
