Morgan Stanley plans to slash 1,600 jobs in what may be just the beginning of a new round of layoffs at large investment banks, this time driven by a deeper reassessment of Wall Street businesses in the face of new regulations and capital standards.

Morgan Stanley, the sixth-largest US bank by assets, plans to begin letting go of the employees, many of whom work in its securities unit, starting this week, two people familiar with the matter said on Wednesday.

A third person involved with plans to cut staff at Morgan Stanley and other large banks said that Morgan Stanley's cuts had been in the works for months, and that more are expected in the future.

"It's hard to look at yourself in the mirror, and say: 'I'm not good at this,'" said the source. But now that management teams are coming to those realizations, he said, they are beginning to make strategic decisions to exit businesses and cut more staff.