* Slone's resignation comes two weeks after chairman left
* Slone joined CLSA in 1988 as regional research director
* Former chair says 'complexities' made him a negative asset (Adds comments from source and from former chair's note to staff)
HONG KONG, March 20 (Reuters) - The chief executive of brokerage CLSA has resigned with more management change likely amid differences over strategy with Chinese parent CITIC Securities Co Ltd (CITIC), people with direct knowledge of the matter said.
Jonathan Slone's departure comes just two weeks after CLSA Chairman Tang Zhenyi resigned from the Asia-focused broker, bought by state-backed CITIC in 2013.
The resignations resulted from CITIC's efforts to revamp CLSA's daily operations, one of the people said on Wednesday, declining to elaborate. The other person with direct knowledge cited differences over strategy.
An agreement between CITIC and CLSA over the brokerage's management, sealed upon acquisition, lapsed in July last year.
"When someone like the chairman (Tang) goes - if he, the poster boy for international Chinese bankers, can't make it work, then you have to wonder," a long-time CLSA banker told Reuters.
The people declined to be identified due to the sensitivity of the matter. A CLSA spokeswoman confirmed Slone's resignation but declined to disclose reasons or comment on other possible changes. CITIC did not respond to a request for comment.
The exits could signal another change in strategy at the broker, widely seen as CITIC's international arm with a mandate to wrest market share helped by its parent's roster of Chinese blue-chip clients bent on expansion.
CLSA has pushed aggressively into investment banking as profit margins in equity broking and research were squeezed by competition and regulatory change. It dropped CITIC from its name and halved U.S. headcount in 2017.
It has also focused on broader Chinese initiatives, notably the multi-billion-dollar Belt and Road project designed to improve Beijing's trade reach and help fund infrastructure in over 60 countries.
Former chairman Tang told Reuters last year that CLSA would add bankers in Southeast Asia to capture Belt and Road business.
Slone joined CLSA in 1988 as regional research director, and oversaw CLSA's global operations in broking, investment banking, asset management, research and sales. He also led the firm's overseas expansion and set up its U.S. operations in 1991.
Slone was a leading force at CLSA in its drive to cut costs and boost revenue by expanding product offerings and entering new markets in Asia. He was also a key ally of Tang.
Tang worked for China's Ministry of Finance and for the World Bank in Washington before joining Citic Group in 2011.
His departure came as a surprise to CLSA staff, as his appointment at was seen as a "gift from Beijing" due to his international exposure, salesmanship and deal-making ability, a third person with direct knowledge of the matter said.
"Along the way toward more success, although I hate to admit, things were not developing totally the way I expected. I came to CLSA two years ago with dream and ambition," Tang wrote in his leaving note to colleagues seen by Reuters.
"But due to all kind of complexities. I suddenly found out, with great pain, that I myself had become a block, or even a negative asset, on the path for CLSA's further growth."
Tang said he was stepping down to let those "who can better align the minds and thoughts across the platforms" lead the firm. He has been replaced by Zhang Youjun, who is also chairman of CITIC Securities.
(Reporting by Julie Zhu, Jennifer Hughes and Sumeet Chatterjee; Editing by Christopher Cushing)