Technology firms are actively looking to increase work force diversity, viewing it as part of their growth strategy, banking veteran Sallie Krawcheck told attendees at a forum hosted by the American Bankers Association earlier this week.

Research shows that adding different backgrounds and perspectives to senior management leads to higher returns and lower volatility. In contrast, the banking industry has become less diverse since the financial crisis, she noted.

"More diverse teams not only outperform less diverse teams but actually outperform more capable teams," Krawcheck, a former high-ranking executive at Citigroup (NYSE: C) and Bank of America (BAC), said during remarks at the Women's Leadership Forum in Washington on Wednesday

During stressful times, people are apt to surround themselves with those who are similar to them because of a need for mutual understanding. But this could exacerbate the problem. "Having people at the table who say, 'slow down, I didn't quite get that,' is not a bad thing," she said.

Krawcheck, who was ousted from B of A in 2011 in a management shakeup, pushed attendees to move away from hiring individuals in favor of building the "best team." She said such a shift would require removing soft biases in the industry that bar employees of different backgrounds from advancing.

Warmly received by the audience, Krawcheck fluidly moved from statistical analysis to, at times, cracking jokes. She advised women in banking to constantly seek feedback, find mentors and sponsors to help guide their careers and focus on external networking.

The Christmas after she left B of A, "holiday cards from Bank of America colleagues were down 95%," she said. "That's not an estimate."

Successful financial services firms realize that women are a "core part" of the business, she said. Women live longer and often retire with less money than men, so they view their investments differently and are more deliberative about decisions, she noted.

"Women very much think about the future and what we want for our children and our grandchildren, so put it in those terms rather than trying to beat the market," she said.

Social media can be a great way to connect with female customers. But the message must change from "let me tell you about myself" to being more engaging.

"Don't sell to me," she said. "Engage with me."