Execution difficulties refer to the challenges traders face when attempting to execute trades in financial markets. The difficulties you mentioned are:

1. *Wide bid-ask spreads*: The difference between the best available buy and sell prices is large, making it costly to execute trades.

2. *Limited market depth*: The availability of tradeable quantities at the best bid and ask prices is low, making it difficult to execute large trades.

3. *High volatility*: Rapid and significant price movements make it challenging to execute trades at desired prices.

4. *Order book fragmentation*: The fragmentation of order books across multiple trading venues and platforms makes it difficult to access liquidity and execute trades efficiently.

Additional execution difficulties include:

1. *Liquidity imbalance*: Temporary or persistent imbalances between buy and sell orders, leading to execution difficulties.

2. *Information asymmetry*: Some market participants have access to better information or technology, making it difficult for others to execute trades fairly.

3. *Market congestion*: High volumes of trades and orders overwhelm the market, causing execution delays and difficulties.

4. *Technological issues*: Technical problems with trading systems, networks, or platforms hinder trade execution.

5. *Regulatory constraints*: Trading restrictions, such as circuit breakers or trading halts, limit the ability to execute trades.

6. *Market structure complexities*: Complexities in market structure, such as multiple trading venues and dark pools, make it challenging to execute trades efficiently.

These execution difficulties can result in:

- Increased trading costs

- Reduced trading activity

- Decreased market efficiency

- Increased market volatility

- Decreased investor confidence

- Increased risk of market disruptions and flash crashes.