1. Firms are struggling to bring in revenues. Fixed costs have already risen considerably, and further base salary hikes are unlikely now.
2. Increased regulation and capital rules has impacted profits, meaning that bankers just aren't as valuable a commodity as they once were.
3. The performance bar has been raised - an increase in salary is no longer a given simply for turning up for work. In future, firms will adopt a much more selective approach, and only hike base salaries for those who are deemed to have added real value to the business.
4. Supply and demand. There are now more bankers chasing fewer jobs.
5. Pressure from institutional shareholders. The 'shareholder spring' has meant that firms are much more accountable on pay, and payroll costs will come under much more scrutiny in future.
6. Politics - it's no longer good for business to be seen paying outsized rewards.
7. The good times are over, as financial markets firms reinvent themselves as leaner, more boring and cost-conscious organisations.
8. The increase in the use of technology is resulting in fewer human interventions, less jobs and smaller base salaries.
9. The general realization that you don't need to pay huge base salaries to attract and retain the fairly average individuals needed for most roles in a financial markets firm.