Nov 29 (Reuters) - Activist investor Ancora Holdings Group LLC in a letter to Berry Global Group Inc (BERY.N) on Monday urged the plastic maker"s board to initiate a review of strategic alternatives, including a sale or go-private transaction. Ancora, which owns about a 1% stake in Berry, said it believes the company could fetch a valuation of $100 per share or more through a sale. Shares of Berry rose 1.4% to $67.40 in premarket trade. They have risen about 18% this year. The investor also asked the board to raise its repurchase authorization to $1 billion, up from $50 million Berry authorized last week. Last year, Canyon Capital Advisors LLC also called on the company to sell some of its non-core assets to help cut its debt.