TORONTO (Reuters) - Canadian investors will face an awkward question if a foreign player succeeds in buying Potash Corp: Where do I put my money now?

The deal, which could rank as 2010's biggest global takeover, would bring a nice boost during a tough year for local shareholders, mutual and pension funds - BHP Billiton's $39 billion bid is so large it triggered a brief rise in the Canadian dollar.

But a successful bid for the world's No.1 fertiliser maker would also remove the sixth-largest company from the Toronto Stock Exchange. That prospect has revived a debate on the "hollowing out" of Canada's main stock market.

"If it does get delisted from the TSX, that's a negative...It reduces the presence of the TSX in general and it makes our job a lot harder if there are less companies that are of larger (capitalisation)," said Andrew Parkinson, a fund manager with Vancouver-based Van Arbor Asset Management.

Many Canadian fund managers regard Potash Corp. as one of the crown jewels in the resource sector. It is by far the largest producer of the crop nutrient and plays a key role in setting the price of fertiliser globally.

During the grain price rally of 2008, the stock briefly topped C$246 in value, making it the largest company on the Toronto Stock Exchange by market capitalization, a spot now held by Royal Bank of Canada.

The miner closed at C$157.06 on Friday. It accounted for more than four percent of the blue chip S&P/TSX 60 index and nearly three percent of the broader S&P/TSX composite index .