The cross ownership is difficult to fully calculate, but a...

The cross ownership is difficult to fully calculate, but a simplistic read is that BKW own 42% of SOL.
If you forget about the holding that SOL has in BKW, and just look at the current share prices of both, the BKW holding in SOL is worth around 2.78 billion, against a market cap of BKW of only 2.25 billion.
That means that the rest of the BKW business is valued at negative half a billion, even though it’s a profitable business.
Historically both SOL and BKW have been grossly undervalued, but that now only applies to BKW since the SOL share price took off.