brackets equation latex
documentclass{article}
usepackage{amsmath}
begin{document}
begin{equation}
  D_{it} =
    begin{cases}
      1 & text{if bank $i$ issues ABs at time $t$}\
      2 & text{if bank $i$ issues CBs at time $t$}\
      0 & text{otherwise}
    end{cases}       
end{equation}
end{document}
