At present, the top 10 exchanges on CoinMarketCap based on volume are listed below. This list has changed a lot in 24 months.

1 Staggering regional competition between exchanges.
There has been a gross proliferation of trading exchanges. Regional interests and trends continue to result in predictable arbitrage opportunities and inefficiencies.

Upbit
Binance
Bithumb
OKEx
Bitfinex
Huobi
Bittrex
HitBTC
Kraken
GDAX
The current BTC/USD spreads* on Token Spread are:

*More exchanges being added very soon.

1. Inability of exchanges to keep pace with demand.
   Kraken was recently down for 48+ hours while upgrading their trading platform. This is what response times look like post-upgrade:

This is not meant to pick on Kraken, a company that has raised millions in capital, but to illustrate just how hard it is to keep up with demand. It’s very easy to say “let’s start an exchange.” It’s a different thing altogether to achieve a level of scale, stability and super low response times like Etrade or Interactive Brokers.

API connectivity across the major crypto exchanges has proven to be highly unpredictable, without exception. This has been one of the big learnings from building Token Spread.

1. Massive proliferation of individual cryptocurrencies.
   There are currently over 50 legitimate contenders for the next best cryptocurrency. While Bitcoin and Ethereum are the clear leaders, there is an arms race for the next best blockchain. Regional influences and the unpredictable addition of new currencies to exchanges around the globe will continue to bring persistent arbitrage opportunities. Because cryptocurrencies are decentralized in nature, with the community able to host its own nodes, there can be no predictable and centralized authority over the global exchanges, protocols, or methods of transfer and remuneration.

2. Security breaches and hacking will continue to destabilize the environment.
   NiceHash hacked for $63M in Bitcoin.

CEX breached for 2M in user data.

Mt. Gox hacked or $473M in Bitcoin.

Ethereum DAO hack for $70M in Ethereum.

Bitfinex hacked for $72M in Bitcoin.

CoinDash ICO compromised for $7M in Ethereum.

1. Regulators will not be able to keep pace with the proliferation of exchanges.
   Regulation will keep the cryptocurrency environment unstable, with large players being handicapped at random, as we’ve seen with Bitfinex in China and may soon see in South Korea and the United States.

Regulation will also cause exchanges to move to more favorable countries. Moves like this will cause significant disruption.