Shares of telecom leader T-Mobile US (TMUS -4.33%) sank as much as 4.6% today, before rebounding to a 4% decline as of 1 p.m. ET.Shares fell on news that major investor SoftBank sold a large block of T-Mobile shares. However, looking at SoftBank's other business endeavors, it's probably not too much of a concern for T-Mobile shareholders.Masayoshi Son likely needs some cashToday, Bloomberg reported that SoftBank sold about $4.8 billion shares of T-Mobile, totaling 21.5 million shares at a price of$224 per ...