Down 50% in a year, why are Treasury Wine shares sinking on Monday?

Treasury Wine Estates Ltd (ASX: TWE) shares are taking a tumble today.

Shares in the S&P/ASX 200 Index (ASX: XJO) global wine company closed on Friday trading for $5.82. In morning trade on Monday, shares are changing hands for $5.61, down 3.6%.

For some context, the…