Section 513. Purchase, redemption and certain other transactions by a corporation with respect to its own shares

(a) Notwithstanding any authority  contained  in  the  certificate  of
  incorporation,  the  shares of a corporation may not be purchased by the
  corporation, or, if redeemable, convertible or exchangeable shares,  may
  not  be redeemed, converted or exchanged, in each case for or into cash,
  other property, indebtedness or  other  securities  of  the  corporation
  (other than shares of the corporation and rights to acquire such shares)
  if the corporation is then insolvent or would thereby be made insolvent.
  Shares may be purchased or redeemed only out of surplus.
    (b)  When  its  redeemable,  convertible  or  exchangeable  shares are
  purchased by the corporation within the period during which such  shares
  may   be   redeemed,  converted  or  exchanged  at  the  option  of  the
  corporation, the purchase price thereof shall not exceed the  applicable
  redemption,  conversion  or  exchange price stated in the certificate of
  incorporation. Upon a redemption, conversion  or  exchange,  the  amount
  payable  by the corporation for shares having a cumulative preference on
  dividends may include the  stated  redemption,  conversion  or  exchange
  price  plus  accrued  dividends  to the next dividend date following the
  date of redemption, conversion or exchange of such shares.
    (c) No domestic corporation which is  subject  to  the  provisions  of
  section  nine  hundred twelve of this chapter shall purchase or agree to
  purchase more than ten percent of the stock of the  corporation  from  a
  shareholder  for more than the market value thereof unless such purchase
  or agreement to purchase is approved by  the  affirmative  vote  of  the
  board of directors and a majority of the votes of all outstanding shares
  entitled  to  vote  thereon  at  a  meeting  of  shareholders unless the
  certificate of incorporation requires a greater percentage of the  votes
  of the outstanding shares to approve.
    The  provisions of this paragraph shall not apply when the corporation
  offers to purchase shares from all holders of stock or for  stock  which
  the holder has been the beneficial owner of for more than two years.
    The  terms "stock", "beneficial owner", and "market value" shall be as
  defined in section nine hundred twelve of this chapter.