Why did AMBR's operating expenses surge in Q4 2022?

AMBR's operating expenses surged in Q4 2022 due to several factors: 1. **Discretionary Net Investment Securities Losses**: The company reported discretionary net investment securities losses in Corporate amounting to $959 million, resulting from the repositioning of the portfolio by selling US treasuries and mortgages. This indicates a significant financial decision that led to a negative impact on the quarter's financial results. 2. **Strategic Portfolio Rebalancing**: The repositioning of the portfolio suggests a strategic move to align with market conditions or internal goals. Such moves can be costly in the short term but may be beneficial in the long term if they lead to improved asset quality or reduced risk. In conclusion, AMBR's operating expenses surge in Q4 2022 primarily due to discretionary net investment securities losses and strategic portfolio rebalancing.