 Shares of Pitney Bowes Inc. PBI, -15.58 tumbled 15.6 in midday trading Tuesday, enough to pace the NYSEs decliners, after the shipping and mailing company reported fourth-quarter profit that fell below expectations, amid disappointing domestic parcel volumes. Net income fell to 1.3 million, or 1 cent a share, from 20.3 million, or 11 cents a share, in the year-ago period. 