Numerous people have said that Greg Abel is an operations guy, not an investments guy, but I think Greg made it pretty clear that he will be managing the investments. As he stated in the shareholder letter,

"At Berkshire, equity investments are fundamental to our capital allocation activities; responsibility
ultimately resides with me as CEO. Ted Weschler manages about 6% of our investments, including
a portion of the portfolio formerly overseen by Todd Combs."

As of Dec 31 Berkshire's investments were allocated as follows:

Cash and cash equivalents, $47.7 billion, or 6.8%
Short-term T-Bills, $321.4 billion, 45.6%
Fixed maturity investments, $17.8 billion, 2.5%
Equities, $297.8 billion, 42.3%
Equity method investments, $20.0 billion, 2.8%

total, $704,725 billion, 100%

We have to wish Greg the best in managing this huge investment portfolio. Luckily he has some good advisors.