The probability that J.P. Morgan Chase & Co. will complete its proposed acquisition of Bear Stearns Companies, Inc. has increased under the amended deal announced yesterday, says Fitch Ratings.

That said, the rating agency has not modified its ratings of Bear Stearns, as significant risk to Bear Stearns debtholders remains if the transaction is not completed.

Fitch says it believes that the motivation to amend the terms of this transaction on the part of all parties involved was primarily to reduce the uncertainty that J.P. Morgan Chase will complete the acquisition. It notes that the amended terms call for J.P. Morgan Chase to pay significantly more for the firm, albeit still substantially less than the last reported book value, and to assume somewhat more risk with respect to certain Bear Stearns’ assets.

Offsetting this, the transaction is considerably more likely to be completed, it adds. Under the revised terms, J.P. Morgan Chase is expected to have 39.5% of Bear’s shares to vote. In addition the merger agreement limits qualifying alternative bids to those from other institutions that have, at minimum, the equivalent level of financial wherewithal (including liquidity and capital) as J.P. Morgan Chase to provide the same comprehensive guarantees, and, at the same time, enter financing and support arrangements with the Federal Reserve sufficient to enable Bear Stearns ‘to conduct business in the ordinary course.’

Regulatory and board approvals for this transaction have already been received, although the transaction remains subject to shareholder approval. Fitch notes that as part of the amended agreement, the shareholder vote will remain open for the lesser of 120 days or until the transaction is approved. This is in contrast to the original agreement which called for the shareholder vote to remain open for up to 12 months.