def plot_sector_allocations(returns, sector_alloc, ax=None, **kwargs):
if ax is None:<EOL><INDENT>ax = plt.gca()<EOL><DEDENT>sector_alloc.plot(title='<STR_LIT>',<EOL>alpha=<NUM_LIT:0.5>, ax=ax, **kwargs)<EOL>box = ax.get_position()<EOL>ax.set_position([box.x0, box.y0 + box.height * <NUM_LIT:0.1>,<EOL>box.width, box.height * <NUM_LIT>])<EOL>ax.legend(loc='<STR_LIT>', frameon=True, framealpha=<NUM_LIT:0.5>,<EOL>bbox_to_anchor=(<NUM_LIT:0.5>, -<NUM_LIT>), ncol=<NUM_LIT:5>)<EOL>ax.set_xlim((sector_alloc.index[<NUM_LIT:0>], sector_alloc.index[-<NUM_LIT:1>]))<EOL>ax.set_ylabel('<STR_LIT>')<EOL>ax.set_xlabel('<STR_LIT>')<EOL>return ax<EOL>
Plots the sector exposures of the portfolio over time.

Parameters
----------
returns : pd.Series
    Daily returns of the strategy, noncumulative.
     - See full explanation in tears.create_full_tear_sheet.
sector_alloc : pd.DataFrame
    Portfolio allocation of positions. See pos.get_sector_alloc.
ax : matplotlib.Axes, optional
    Axes upon which to plot.
**kwargs, optional
    Passed to plotting function.

Returns
-------
ax : matplotlib.Axes
    The axes that were plotted on.