Who knifed AAPL?

June 16, 2011, 7:43 PM UTC

With the Dow up and no negative news on the wire, the stock fell off a cliff Thursday

Thursday was another one of those bizarre trading days for Apple (AAPL). The stock opened higher, flirted with some prices north of $328 in the morning and made it through the early afternoon without suffering much damage, despite the turmoil in Greece.

Then, at about 1:50 p.m., the volume jumped and the stock fell off a cliff, dropping at one point to 318.33, more than $10 below its high for the day.

The last time Apple closed below $320 was in early December. Since then, the company has reported two quarters of 75.2% and 92.2% earnings growth, respectively. It’s not clear what it has done to deserve this kind of treatment.

[UPDATE: As it turns out, Research in Motion (RIMM) was the stock that deserved to be disrespected Thursday. When the company reported quarterly revenues that were worse than expected and warned of future layoffs, the stock fell 16% in after-hours trading.]

Among the dwindling numbers of retail Apple investors, there were the usual cries of market manipulation and calls for reform of the weekly options markets, which some believe have become the tail that wags the underlying stock.

A check of the open interest in Apple weeklys Thursday showed nearly 40,000 puts at $320 and tens of thousands of outstanding calls at every price point between $330 and $360. If  Apple closes anywhere between $320 and $330 on Friday — the so-called Max Pain point — all those options will expire worthless.

The stock recovered somewhat in the last hour of trading to close at $325.16, down $1.59 (0.49%) for the day.

Below the fold: A snapshot of Thursday’s open interest in Apple weeklys.

Click to enlarge. Source: thinkorswim