Consider a scenario where a wealth management firm is tasked with rebalancing a client's multi-asset portfolio consisting of equities, bonds, and alternative investments. The portfolio has deviated from its target asset allocation of 60% equities, 30% bonds, and 10% alternatives. The firm must execute rebalancing trades on a volatile trading day amidst significant market news.

Discuss the execution strategies that the firm should consider for this rebalancing activity, taking into account factors such as market conditions, liquidity of the assets involved, potential market impact, and trade costs. Illustrate the advantages and disadvantages of at least three different execution strategies, including but not limited to VWAP (Volume Weighted Average Price), TWAP (Time Weighted Average Price), and implementation shortfall. Provide a thorough analysis of how the chosen strategies align with the firm's objectives for effective portfolio management and risk mitigation.