NEW YORK (Reuters) - Citigroup's ( C/PN ) new head of wealth, Andy Sieg, further reshuffled his leadership team by appointing two executives on Wednesday who will help drive his efforts to retain clients' investment assets.

Sieg tapped Kris Bitterly to run Wealth at Work, a business that serves clients through their employers, according to a memo seen by Reuters.

He also hired Keith Glenfield, with whom he worked closely at Merrill Lynch Wealth Management, to succeed Bitterly as head of investment solutions when she takes on her new role in September.

"It is time for a laser-like focus on winning our clients' investment assets," to expand beyond their traditional banking and lending needs, Sieg wrote. He will address investors later Wednesday in his first remarks at a public conference since joining Citi in September.

Bitterly, who currently leads investment solutions, will succeed Joe Ryan, who is running the Wealth at Work business on an interim basis after the departure of Naz Vahid was announced last month.

Sieg has pushed a growth strategy based on capturing the estimated $5 trillion in assets that Citi's wealthy clients have invested with other banks or asset managers.

He also hired Dawn Nordberg from Morgan Stanley to lead integrated client engagement, it announced last week. The new wealth function is intended to boost collaboration, including with the company's banking unit led by Viswas Raghavan, who started earlier this month.

Citigroup ( C/PN ) CEO Jane Fraser has also emphasized getting a "fair share" of its client assets invested elsewhere, she told investors in April.

"That will help us get the returns where they need to be in this business in the medium term," she said.

The wealth division poses the biggest challenge for Citi to improve its operational performance and shift its mix of businesses to reduce its reliance on lending, Bank of America analysts led by Ebrahim Poonawala wrote in a note last week.

"Management will need to make the case for how Citigroup ( C/PN ) can effectively compete against industry behemoths such as UBS and HSBC when comparing to global banks and the likes of Morgan Stanley, JPMorgan and Bank of America in the U.S."

If the turnaround is not successful, the bank may consider strategic alternatives for the division, he added.