diff --git a/matlab/@dynSeries/uminus.m b/matlab/@dynSeries/uminus.m
new file mode 100644
index 000000000..21eb78aed
--- /dev/null
+++ b/matlab/@dynSeries/uminus.m
@@ -0,0 +1,78 @@
+function A = uminus(B)
+%@info:
+%! @deftypefn {Function File} {@var{A} =} plus (@var{B},@var{C})
+%! @anchor{@dynSeries/uminus}
+%! @sp 1
+%! Overloads the uminus method for the Dynare time series class (@ref{dynSeries}).
+%! @sp 2
+%! @strong{Inputs}
+%! @sp 1
+%! @table @ @var
+%! @item B
+%! Dynare time series object instantiated by @ref{dynSeries}.
+%! @item C
+%! Dynare time series object instantiated by @ref{dynSeries}.
+%! @end table
+%! @sp 1
+%! @strong{Outputs}
+%! @sp 1
+%! @table @ @var
+%! @item A
+%! Dynare time series object.
+%! @end deftypefn
+%@eod:
+
+% Copyright (C) 2012 Dynare Team
+%
+% This file is part of Dynare.
+%
+% Dynare is free software: you can redistribute it and/or modify
+% it under the terms of the GNU General Public License as published by
+% the Free Software Foundation, either version 3 of the License, or
+% (at your option) any later version.
+%
+% Dynare is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU General Public License
+% along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
+
+% AUTHOR(S) stephane DOT adjemian AT univ DASH lemans DOT fr
+
+A = dynSeries();
+
+A.freq = B.freq;
+A.nobs = B.nobs;
+A.vobs = B.vobs;
+A.init = B.init;
+A.name = repmat({'--NA--'},A.vobs,1);
+A.data = -(B.data);
+
+
+%@test:8
+%$ % Define a datasets.
+%$ A = rand(10,2);
+%$
+%$ % Define names
+%$ A_name = {'A1';'A2'};
+%$
+%$ t = zeros(4,1);
+%$
+%$ % Instantiate a time series object.
+%$ try
+%$    ts1 = dynSeries(A,[],A_name,[]);
+%$    ts2 = -ts1;
+%$    t(1) = 1;
+%$ catch
+%$    t = 0;
+%$ end
+%$
+%$ if length(t)>1
+%$    t(2) = dyn_assert(ts2.vobs,2);
+%$    t(3) = dyn_assert(ts2.nobs,10);
+%$    t(4) = dyn_assert(ts2.data,-A,1e-15);
+%$ end
+%$ T = all(t);
+%@eof:8