When it comes to investing in China's volatile stock market, investors should heed the immortal words of American philosopher Yogi Berra: “It ain't over till it's over.”

So until it is clear that China's financial crisis has passed, investors are advised to focus on buying weekly puts on the Deutsche X-Trackers Harvest CSI 300 China A-Shares Fund (ticker: ASHR ).

The put positions investors to profit as China's leaders struggle to address a crisis that has broadly shaken international investor confidence in China's financial markets and political leaders.

We have been bearish on Chinese stocks since late July. We recently recommended investors buy bearish October $30 puts on the Deutsche X-Trackers Harvest CSI 300 China A-Shares Fund after taking profits on October $ 40 puts.

With ASHR at $32.48, investors can buy ASHR's September $ 29 puts that expire Friday for 20 cents. If ASHR declines to $28 by Friday's close, the puts are worth $ 1.

The put purchase is only suitable for aggressive investors.

As options contracts approach expiration dates, they become increasingly sensitive to movements in the associated securities. This makes weekly contracts, which usually never cost much, potentially worth a lot if the underlying security moves in the right direction. If the trade is a bust, the loss is not significant because little money was wagered.

The addition of weekly puts to a previously recommended ASHR October put purchase reflects a view that China's leaders may face a steeper-than-expected learning curve handling a financial crisis. The government is trying to quash bearish investor sentiment by threatening police action against short sellers and arresting people for spreading negative sentiment about stocks . The developments do not engender investor confidence.

The weekly put trade anticipates China's leaders will make more clumsy moves that will startle shell-shocked investors and perhaps send stocks even lower.

While these short put trades will appeal to aggressive investors, we argue that they are best executed as complements to our long ASHR October $30 put position. The reasoning? Weekly options are a way to time the market. But it is very hard to successfully time the market. The October puts thus even the odds.

Other investors are starting to join us in the October expiration. In recent trading, an investor bought 5,000 ASHR October $ 30 puts.

We favor the October expiration because it captures an important political event that is not on the radar of many investors. The 18th Communist Party of China Central Committee will hold its fifth plenary session in Beijing in October. The meeting is expected to focus on a national development plan for 2016 to 2020.

This event has added significance this year due to the financial crisis and questions about China's leadership. If the plenum fails to assuage investor concerns about China's economic growth, the plenum could become a tradable event by increasing pressure on Chinese stocks.

To be sure, investor sentiment is already shaky. Many investors think Chinese stocks are still too expensive – even after recent extraordinary declines that saw ASHR drop some 18% over the past month. ASHR is considered a proxy for mainland China stocks.

As my colleague at Barron's Asia , Daniel Shane, recently noted, the average stock in the Shanghai Stock Exchange Composite Index (SHCOMP: IND) now trades at 15 times earnings, a significant fall from the peak of about 22 times in June. But Shane says Chinese stocks are still expensive compared with the 10 times they traded at last year before stock market surged. The Shanghai index would have to fall to about 2,700 to return to a P/E of 10. The index was recently around 3,205.

Until valuations improve, or China's leaders regain mastery of the situation, remember what Yogi Berra said and think about buying bearish puts on China's stock market.