Nathan Flynn will focus on coverage of Midwest and Southeast borrowers and provide an assist on structuring and project financing more broadly, Siebert said.
Tishelman, a 40-year market vet, comes to Siebert from UBS Financial Services, where he was a managing director and head of issuance strategies and municipal sales.
Public finance veterans Marvin Markus and Mark Liff join Siebert as managing directors to focus on expanding the firm's infrastructure and higher education practices.
UBS' move this week to cut some banking positions marked a reversal of its five-year growth trend as the bank rebooted its municipal underwriting business.