Tech investors SoftBank Group and Ark Investment are among the firms discussing participation in a major Tether fundraise that could  value the stablecoin issuer at $500 billion, according to a Friday Bloomberg report. The two groups’ interest follows three days after news that El Salvador-based Tether was looking to raise$15-20 billion for a 3% equity stake. Bloomberg first reported this story, citing two unnamed sources, although another source said the amount could be less.  The initiative could help pu ...