Diana Shipping has raised the prospect of cutting its $27.34-per-share takeover proposal for Genco Shipping & Trading after claiming the US-listed owner’s fleet has shed $50m in value since early June. The Athens-based owner cited VesselsValue data placing Genco’s 43-ship fleet at $1.433bn on July 28, down 3.4% from a peak of $1.483bn in early …