Exhibit 10(b)(5)(b)

EXECUTION COPY

AMENDMENT NO. 1 dated as of March 6, 2008 among NewStar Structured Finance
Opportunities, LLC (the “Issuer”), NewStar Financial, Inc., as limited recourse
provider (the “Limited Recourse Provider”), MMP-5 Funding, LLC, Fenway Capital,
LLC, Fenway Funding, LLC, Natixis Financial Products Inc. (as successor to IXIS
Financial Products Inc.), as agent for the Investors (in such capacity, together
with its successors in such capacity, the “Investor Agent”) and U.S. Bank
National Association, as trustee (in such capacity, together with its successors
and assigns, the “Trustee”).

Reference is made to the Note Purchase Agreement dated as of March 21, 2006 (as
amended, modified and/or supplemented prior to the effectiveness hereof, the
“Note Purchase Agreement”) among the Issuer, the Limited Recourse Provider,
MMP-5 Funding, LLC, as Swingline Investor, the Investors party thereto, the
Investor Agent and the Trustee. The parties to the Note Purchase Agreement wish
to amend the Note Purchase Agreement to the extent provided herein. Accordingly,
the parties hereto hereby agree as follows:

Section 1. Definitions. Terms used but not defined herein have the respective
meanings given to such terms in the Note Purchase Agreement.

Section 2. Amendments to Note Purchase Agreement. Effective as of September 29,
2006, but subject to the execution and delivery of this Amendment No. 1 by each
of the intended parties hereto, the Note Purchase Agreement shall be amended as
set forth below.

(a) The definition of Advance Credit Balance in Section 1.1 of the Note Purchase
Agreement is amended to read in its entirety as follows:

““Advance Credit Balance” means a running balance (which balance may never be
less than zero) that may be increased or decreased, as applicable, by the
following procedures:

 

  i. On any date a Collateral Debt Security (or multiple Collateral Debt
Securities) is purchased by the Issuer and the portion of the Purchase Price
funded by an Advance is less than the marginal increase of the Maximum Advance
before and after giving effect to such purchase, then the excess of the marginal
increase over the Advance used for such purchase will be added to the Advance
Credit Balance.

 

  ii.

On any date that a Moody’s Rating is assigned to a Collateral Debt Security by
the receipt of a rating by Moody’s pursuant to clause (g) of the definition of
Moody’s Rating and the Moody’s Rating actually assigned is different than the
Interim Rating deemed pursuant to such clause (g), an amount designated by
NewStar will be added to the Advance Credit Balance not to exceed (x) the
Maximum Advance plus Cash on deposit in the Collateral Account representing
Principal Proceeds minus (y) outstanding Advances, after giving effect to such

--------------------------------------------------------------------------------

 

assigned Moody’s Rating. For the avoidance of doubt, if (x) minus (y) results in
a negative number, the Advance Credit Balance will be reduced by such absolute
amount thereof.

 

  iii. On any date that the Issuer (or the Collateral Manager on behalf of the
Issuer) requests an Advance and designates the Advance (or a portion of such
Advance) as an Advance Credit Balance withdrawal (an “Advance Credit Balance
Withdrawal”), the proceeds thereof will be transferred to NewStar (or, in the
circumstances contemplated by Section 6.4, deposited into the Collateral
Account) and the Advance Credit Balance will be reduced accordingly by the
amount of each such withdrawal; provided, any Advance will be permitted to be
made in accordance with this clause only if, after giving effect to such
withdrawal, the Advance Credit Balance is greater than or equal to zero;
provided further, that no Limited Recourse Event has occurred.”

(b) The definition of Over-Advanced Amount in Section 1.1 of the Note Purchase
Agreement is amended to read in its entirety as follows:

““Over-Advanced Amount” means, as of any day, the greater of (i) zero (0) and
(ii) an amount equal to the aggregate outstanding principal balance of the
Advances and Swingline Advances as of such date and the Advance Credit Balance
as of such date reduced by any Cash on deposit in the Collateral Account
representing Principal Proceeds and Eligible Investments in the Collateral
Account representing Principal Proceeds minus the Maximum Advance as of such
day.”

(c) Section 3.2(b) of the Note Purchase Agreement is amended to read in its
entirety as follows:

“(b) immediately after such Funding (and the intended use of the proceeds
thereof), the aggregate outstanding principal amount of the Advances and the
Swingline Advances shall not exceed the sum of (x) the Maximum Advance and
(y) Cash on deposit in the Collateral Account representing Principal Proceeds
and the aggregate outstanding principal amount of the Swingline Advances shall
not exceed the Swingline Amount;”

(d) For the avoidance of doubt, it is hereby acknowledged and agreed by the
parties hereto that proceeds of Advances deposited in the Collateral Account
shall constitute Principal Proceeds for purposes of the Note Purchase Agreement.

Section 3. Representations and Warranties. The Issuer represents and warrants to
each Investor and the Investor Agent that after giving effect to this Amendment
No. 1, (a) no Default shall have occurred and be continuing and (b) the
representations and warranties of the Issuer contained in the Note Purchase
Agreement and each of the other Financing Documents shall be true and correct,
except where such representation or warranty is qualified by materiality or
Material Adverse Effect, in which case such representation and warranty shall be
true and

 

2

--------------------------------------------------------------------------------

correct as so qualified as of such date (unless stated to relate solely to an
earlier date, in which case such representation and warranty shall be true and
correct in all material respects as of such earlier date).

Section 4. Continuing Effectiveness. Except as amended hereby, the Note Purchase
Agreement shall remain unchanged and in full force and effect, and each
reference to the Note Purchase Agreement in the Financing Documents shall be
deemed to be a reference to the Note Purchase Agreement as amended hereby.

Section 5. Counterparts. This Amendment No. 1 may be signed in any number of
counterparts, each of which shall be an original, with the same effect as if the
signatures thereto and hereto were upon the same instrument. Delivery of an
executed signature page of this Amendment No. 1 by facsimile transmission shall
be effective as delivery of a manually executed counterpart hereof.

Section 6. Governing Law. This Amendment No. 1 shall be construed in accordance
with and be governed by the laws of the State of New York.

 

3

--------------------------------------------------------------------------------

IN WITNESS WHEREOF, the parties hereto have caused this Amendment No. 1 to be
duly executed as of the day and year first above written.

 

NEWSTAR STRUCTURED FINANCE OPPORTUNITIES, LLC By:   /s/ John J. Frishkopf  
Name:    John J. Frishkopf   Title:   Managing Director

NEWSTAR FINANCIAL, INC.

    as Limited Recourse Provider

By:   /s/ John J. Frishkopf   Name:   John J. Frishkopf   Title:   Managing
Director

--------------------------------------------------------------------------------

MMP-5 FUNDING, LLC

    as Investor and Swingline Investor

By:   /s/ Bernard J. Angelo   Name:    Bernard J. Angelo   Title:   Vice
President

--------------------------------------------------------------------------------

FENWAY CAPITAL, LLC

    as Investor

By:   /s/ Bernard J. Angelo   Name:    Bernard J. Angelo   Title:   Vice
President

FENWAY FUNDING, LLC

    as Investor

By:   /s/ Bernard J. Angelo   Name:   Bernard J. Angelo   Title:   Vice
President

--------------------------------------------------------------------------------

NATIXIS FINANCIAL PRODUCTS INC. (as successor to IXIS Financial Products Inc.)

    as Investor Agent

By:   /s/ Ralph J. Inglese   Name:    Ralph J. Inglese   Title:   Managing
Director By:   /s/ Christopher Hayden   Name:   Christopher Hayden   Title:  
Managing Director

--------------------------------------------------------------------------------

U.S. BANK NATIONAL ASSOCIATION

    as Trustee

By:   /s/ Kyle Harcourt   Name:    Kyle Harcourt   Title:   Vice President