Table of Contents
securities subject to lock-up agreements. There are no existing agreements between the underwriters and any of our stockholders who will execute a lock-up agreement providing consent to the sale
of shares prior to the expiration of the restricted period.
NASDAQ Market Listing
We have applied to list our common stock on the NASDAQ Global Market under the symbol "PRTO."
Short Sales, Stabilizing Transactions, and Penalty Bids
In order to facilitate this offering, persons participating in this offering may engage in transactions that stabilize, maintain, or
otherwise affect the price of our common stock during and after this offering. Specifically, the underwriters may engage in the following activities in accordance with the rules of the SEC.
Short sales. Short sales involve the sales by the underwriters of a greater number of shares than they are required to purchase in the
Covered short sales are short sales made in an amount not greater than the underwriters' option to purchase additional shares from us in this offering. The underwriters may close out any covered short
position by either exercising their option to purchase shares or purchasing shares in the open market. In determining the source of shares to close out the covered short position, the underwriters
will consider, among other things, the price of shares available for purchase in the open market as compared to the price at which they may purchase shares through the option to purchase additional
shares. Naked short sales are any short sales in excess of such option to purchase additional shares. The underwriters must close out any naked short position by purchasing shares in the open market.
A naked short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of the common stock in the open market after pricing that could
adversely affect investors who purchase in this offering.
Stabilizing transactions. The underwriters may make bids for or purchases of the shares for the purpose of pegging, fixing, or
maintaining the price
of the shares, so long as stabilizing bids do not exceed a specified maximum.
Penalty bids. If the underwriters purchase shares in the open market in a stabilizing transaction or syndicate covering transaction,
they may reclaim
a selling concession from the underwriters and selling group members who sold those shares as part of this offering. Stabilization and syndicate covering transactions may cause the price of the shares
to be higher than it would be in the absence of these transactions. The imposition of a penalty bid might also have an effect on the price of the shares if it discourages resales of the shares.
transactions above may occur on the NASDAQ Global Market or otherwise. Neither we nor the underwriters make any representation or prediction as to the effect that the transactions
described above may have on the price of the shares. If these transactions are commenced, they may be discontinued without notice at any time.
The underwriters have informed us that they do not expect to confirm sales of common stock offered by this prospectus to accounts over
which they exercise discretionary authority without obtaining the specific approval of the account holder.