An investor said it has become Clariant’s largest shareholder – with a 15.1 percent stake – and will continue an attempt to block the Swiss chemical group’s proposed $20 billion merger with Huntsman.   White Tale Holdings – a Cayman Island-based partnership between hedge funds Corvex and 40 North – wrote a letter to Clariant’s board to explain its opposition. “Unfortunately, we remain convinced, and increasingly so, that the proposed merger is detrimental to Clariant ...