According to the fund's report at the end of May, it held airline stock worth about $1 billion.

And the airline stocks might not have much lift left in them.

Airline stocks were strong, thanks to recent declines in oil prices.

The saying also seems fitting for investors in airline stocks.

"It's not the best time to own airline stocks," he said.

The cost of oil, and thus fuel, often affects airline stocks.

Aside from the fact that many airline stocks are down these days, the big problem is uncertainty about the deal.

All of which does not necessarily mean that airline stocks are bad investments.

As a result, many airline stocks have jumped sharply in recent months.

Airline stocks have had a nice run this year, but are down 9 percent from their March highs.