May 18 (Reuters) - Spectrum Brands Holdings Inc
* Tourbillon sends letter to spectrum brands' board of directors
* Tourbillon Capital Partners - urges spectrum brands board to evaluate opportunity to enter into a potential downstream merger with HRG Group
* Tourbillon Capital Partners- "believe right transaction with hrg could yield 70-90 pct upside to SPB shares"
* Tourbillon Capital Partners - expect Spectrum's board to form a special committee and seek approval by a majority of spectrum's minority shareholders Source text for Eikon: Further company coverage: