Investors just can't get enough of

Cisco

(CSCO) - Get Report

, as the tech bellwether continues to be the most actively traded

option on the major exchanges today.

The large networking firm announced its quarterly results after the bell Tuesday, posting a third-quarter profit of 3 cents a share, excluding charges. Although the results weren't a surprise due to

guidance from the company, investors were anticipating more visibility from CEO John Chambers. Ahead of earnings, investors

expressed bullish sentiment by buying Cisco

calls, betting that the stock would go up. Yesterday, David Schultz, of

Summit Capital Holdings

, said that if Chambers even hinted at an increase in orders, the stock would pop.

Instead, the conference call was tepid, with Chambers providing little visibility. Cisco

put volume increased on all the major exchanges today, but it's unclear whether investors have grown more bearish on the stock. James Quinn, of

Letco

, the designated primary market maker in Cisco options at the

Chicago Board Options Exchange

, said a shift in sentiment has yet to be determined, but it's possible that the stock is repricing itself after such a watery outlook from Chambers. Quinn believes that most of the activity in Cisco options can be characterized as earnings-related volatility trading. The implied volatility of a stock typically increases around the time quarterly earnings are released. The

CBOE

volatility index inched up 1.89% to 28.06 today but has remained relatively stable over the past two weeks.

The May 20 puts were the most active, trading about 22,000 contracts on an open interest of 36,834. The premium on those puts was most recently listed at $1.20 ($120 per contract). Conversely, the May 20 calls traded more than 35,000 contracts on an open interest of 150,070. The premium on those calls was listed at 75 cents ($75 per contract).

Cisco closed down $1.29, or 6.3%, at $19.09.

BioChem Pharma

(BCHE)

was getting a powerful pop today after Canadian regulators finally approved a $4 billion takeover of the Montreal-based company by the U.K.'s

Shire Pharmaceutical

(SHPGY)

. BioChem traded up $3.19, or 9.8%, to $35.75.

Rumors that the merger was in jeopardy sparked

heavy volume in BioChem options last week. Today, investors grabbed the May 35 calls, which traded about 2,300 contracts on an open interest of 5,133. The premium on those calls is currently listed at $1.45 on the CBOE.