Morgan Stanley, the investment bank that’s cutting 1,600 jobs, is deferring 100 percent of bonuses for some senior bankers and traders over three years, Bloomberg News reported yesterday. The deferrals apply to employees who have both total pay of more than $350,000 and bonuses of at least $50,000. Morgan Stanley last year capped most cash bonuses at $125,000 as it seeks to tie employees to the firm and satisfy regulators’ demands for long-term incentives. Morgan Stanley set aside $5.17 billion for compensation in its investment-banking and trading division in the first nine months of 2012, a 9 percent decline from a year earlier.