SoftBank Group Corp.’s flagship Vision Fund has quietly sold off or written down billions of dollars’ worth of its publicly-listed holdings in recent years, a sign of founder Masayoshi Son’s shift away from the venture capital deals that were once an obsession and toward strategic investments in semiconductors and artificial intelligence.Since the end of 2021, the world’s biggest startup fund has seen its US-listed portfolio shrink by almost $29 billion, as it sold down stakes in companies such ...