(Reuters) - Warren Buffett has made further preparations for donating his fortune after his death.

Buffett, 94, the chairman of Berkshire Hathaway ( BRK/A ), is donating nearly all of his remaining wealth, valued on Friday at $149.7 billion according to Forbes magazine, to a charitable trust overseen by his daughter and two sons.

On Monday, Buffett said three potential successor trustees have been designated to serve if his daughter Susie, 71, and sons Howard, 69, and Peter, 66, cannot serve.

He said each successor trustee is somewhat younger than his children, well known to them and "makes sense to all of us."

Buffett also said he is donating about $1.14 billion of additional Berkshire stock to four family foundations.

He has donated 56.6% of his Berkshire stock to the foundations and to the Bill & Melinda Gates Foundation since pledging in 2006 to give away nearly all his money to charity.

The donations were worth more than $58 billion at the time Buffett gave them, including more than $43 billion to the Gates Foundation.

Buffett has run Berkshire since 1965.