425
Filed by Prosperity Bancshares, Inc.
Pursuant to Rule 425 under the
Securities Act of 1933
Subject Company: American State Financial Corporation
        Commission File No. 1-35388

2
“Safe Harbor”
Statement
“Safe Harbor”
Statement
under the Private Securities Litigation Reform Act of 1995
Statements contained in this presentation which are not historical facts and which
pertain to future operating results of Prosperity Bank and its subsidiaries constitute
“forward-looking statements”
within the meaning of the Private Securities Litigation
reform Act of 1995. These forward-looking statements involve significant risks and
uncertainties. Actual results may differ materially from the results discussed in these
forward-looking statements. Factors that might cause such a difference include, but
are not limited to, those discussed in the company’s periodic filings with the SEC.
Copies
of
the
SEC
filings
for
Prosperity
Bancshares
®
may
be
downloaded
from
the
Internet at no charge from www.prosperitybanktx.com.
In connection with the proposed merger of American State Financial Corporation into Prosperity Bancshares,
Prosperity
Bancshares
will
file
with
the
Securities
and
Exchange
Commission
a
registration
statement
on
Form
S-4
to
register the shares of Prosperity’s common stock to be issued to the shareholders of American State Financial
Corporation. The registration statement will include a proxy statement/prospectus which will be sent to the
shareholders of American State Financial Corporation seeking their approval of the proposed transaction.
WE URGE INVESTORS AND SECURITY HOLDERS TO READ THE REGISTRATION STATEMENT ON
FORM S-4, THE PROXY STATEMENT/PROSPECTUS INCLUDED WITHIN THE REGISTRATION
STATEMENT ON FORM S-4 AND ANY OTHER RELEVANT DOCUMENTS TO BE FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION IN CONNECTION WITH THE PROPOSED TRANSACTION
BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT PROSPERITY, AMERICAN STATE
FINANCIAL CORPORATION AND THE PROPOSED TRANSACTION.

3
Corporate Profile
Corporate Profile
•
A Texas based Financial Holding Company with approximately $10
billion in assets
•
3
rd
largest Texas based commercial bank by Texas deposits
•
Strong
balance
sheet
growth
–
10
year
CAGR
of
24%
loans,
22%
deposits and 23% assets
•
Strong
earnings
growth
–
10
year
CAGR
of
14%
for
EPS
(diluted)
and
27% for net income
•
Shareholder driven with approximately 9% inside ownership
•
Excellent
asset
quality
–
Net
Charge
Offs
/
Average
Loans
of
0.06%
for
three months ending December 31, 2011
•
Excellent
cost
control
–
under
50%
efficiency
ratio
•
Integrated over 30 successful acquisitions over the past 16 years
a Track Record of Success

4
4Q11 Highlights
4Q11 Highlights
•
Net Interest Margin was 3.82% for the fourth quarter 2011
•
Non-
Performing Assets to Average Earning Assets remain low at 0.14%
or $12.052 million
•
Strong Earnings of $36.406 million or $0.77 per share (diluted) and
1.50% Return on Assets for the fourth quarter 2011
•
Tangible Common Equity Ratio improved to 7.00% at December 31,
2011
•
Announced acquisition of Bank of Texas, Austin (total assets of $72.5
million, loans of $29.7 million and deposits of $64.2 million); First
Federal
Bank
Texas,
Tyler
(total
assets
of
$210.6
million,
loans
of
$161.2
million and deposits of $121.2 million); and The Bank Arlington,
Arlington
(total
assets
of
$37.3
million,
loans
of
$21.3
million
and
deposits
$32.8 million)

February 27, 2012
Merger with American State Financial Corp.

6
Strategic Rationale
Strategic Rationale
•
American State merger marks Prosperity’s entry into West Texas in a
significant way:
–
Expands Prosperity west of I-35 and creates a presence in 18 new counties, for a total of 78
counties of operation upon completion
–
American State is ranked in the top three by deposit market share in each of the following
attractive markets: Lubbock, Abilene and Odessa
–
Creates ample opportunities for in-market consolidation in new markets across Texas
•
Creates the second largest bank focused solely on Texas with
approximately $14 billion in assets:
–
Improves Texas deposit market share ranking to the seventh position from number nine
–
Significantly increases the C&I loan portfolio, increasing from approximately $440 million to
over $740 million
–
Complementary balance sheets as American State brings high quality, low cost deposits and
pristine asset quality
Following the merger, Prosperity will be the 51st largest U.S. 
headquartered banking institution

7
Assumptions & Impact
Assumptions & Impact
•
Expected to be approximately 8% accretive to earnings per share
•
The tangible common equity ratio is restored in approximately one year
•
Preliminary loan mark is approximately equal to American State’s
current loan loss reserve
•
Non-deposit fee revenue is enhanced through the merger
•
Through the merger Prosperity will acquire a trust department with $850
million in assets under management

8
Pro Forma Branch Franchise
Pro Forma Branch Franchise
(1)   PB pro forma for pending and recently completed acquisitions: Texas Bankers, East Texas Financial Services and Bank Arlington
(2)   ASFC excludes one drive thru branch in Odessa and eight mobile deposit services for nursing homes that do not retain deposits
Texas Deposit Market Share
PB
(1)
(178)
ASFC
(2)
(37)
Source: SNL Financial and Microsoft MapPoint; Deposit data as of June 30, 2011
Deposits
Market
Branch
in Market
Share
Rank
Institution (ST)
Count
($mm)
(%)
1
JPMorgan Chase & Co. (NY)
676
96,001
20.0
2
Bank of America Corp. (NC)
458
77,630
16.2
3
Wells Fargo & Co. (CA)
713
51,245
10.7
4
BBVA
378
26,016
5.4
5
Cullen/Frost Bankers Inc. (TX)
133
15,188
3.2
6
Comerica Inc. (TX)
144
10,444
2.2
Pro Forma
215
10,093
2.1
7
Capital One Financial Corp. (VA)
184
9,056
1.9
8
Zions Bancorp. (UT)
96
8,499
1.8
9
Prosperity
Bancshares
Inc.
(TX)
(1)
178
7,897
1.6
10
International Bancshares Corp. (TX)
227
6,356
1.3
11
Texas Capital Bancshares Inc. (TX)
12
4,742
1.0
12
Regions Financial Corp. (AL)
87
4,505
0.9
13
BOK Financial Corp. (OK)
48
4,291
0.9
14
PlainsCapital Corp. (TX)
33
3,835
0.8
15
Citigroup Inc. (NY)
107
3,756
0.8
16
First Financial Bankshares (TX)
56
3,186
0.7
17
First National Bank Group Inc. (TX)
60
2,783
0.6
18
Woodforest Financial Group (TX)
203
2,619
0.5
19
ViewPoint Financial Group Inc (TX)
33
2,534
0.5
20
Amarillo National Bancorp Inc. (TX)
16
2,344
0.5
21
Southside Bancshares Inc. (TX)
39
2,242
0.5
22
American
State
Financial
Corp.
(TX)
(2)
37
2,196
0.5
23
Broadway Bancshares Inc. (TX)
40
1,997
0.4
24
Grupo Financiero Banorte
20
1,861
0.4
25
Lone Star Natl Bcshs--TX Inc. (TX)
32
1,860
0.4
Totals (1-25)
4,010
353,085
73.6
Totals (1-591)
6,893
479,707
100.0

9
Balance Sheet Summary
Balance Sheet Summary
As Originally Reported
$ in millions
$0
$200
$400
$600
$800
$1,000
$1,200
$1,400
$1,600
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
Loans
Deposits
Assets
Equity
$0
$1,200
$2,400
$3,600
$4,800
$6,000
$7,200
$8,400
$9,600
Total footings as of 12/31/11
Loans =
$3.766 Billion
Deposits =
$8.060 Billion
Assets =
$9.823 Billion
5 year CAGR
Loans =
12%
Deposits =
17%
Assets =
16%

10
$0.77
$0.70
$3.01
$1.94
$2.09
$2.06
$2.73
$2.41
$0.00
$0.50
$1.00
$1.50
$2.00
$2.50
$3.00
$3.50
2006
2007
2008
2009
2010
2011
4Q 2010
4Q 2011
EPS Growth Diluted
EPS Growth Diluted
*Excluding
the
non-cash
after
tax
impairment
charge
related
to
FNMA/FLHMC
preferred
stock
of
$6.5
million,
EPS
was
$1.94
**Excluding
the
non-cash
after
tax
impairment
charge
related
to
FNMA/FLHMC
preferred
stock
of
$9.1
million,
EPS
was
$1.86
*
**

11
Pro Forma Deposit Composition
Pro Forma Deposit Composition
Prosperity Bancshares, Inc.
American State Financial Corporation
Pro Forma
Deposit Portfolio ($000)
% of Total
Non-interest Bearing DDA
1,972,226
$    
24.5%
Interest Bearing DDA
1,532,701
      
19.0%
MMA & Savings
2,557,023
      
31.7%
CD's & IRA's<100m
968,806
         
12.0%
CD's & IRA's>100m
1,029,498
      
12.8%
Total Deposits
8,060,254
$    
100.0%
Cost of Total Deposits
0.44%
Deposit Portfolio ($000)
% of Total
Non-interest Bearing DDA
561,065
$       
22.8%
Interest Bearing DDA
574,094
         
23.3%
MMA & Savings
642,744
         
26.1%
CD's & IRA's<100m
249,553
         
10.1%
CD's & IRA's>100m
432,073
         
17.6%
Total Deposits
2,459,529
$    
100.0%
Cost of Total Deposits
0.42%
Deposit Portfolio ($000)
% of Total
Non-interest Bearing DDA
2,533,291
$    
24.1%
Interest Bearing DDA
2,106,795
      
20.0%
MMA & Savings
3,199,767
      
30.4%
CD's & IRA's<100m
1,218,359
      
11.6%
CD's & IRA's>100m
1,461,571
      
13.9%
Total Deposits
10,519,783
$  
100.0%
Cost of Total Deposits
0.44%
Source: PB’s 4   Quarter 2012 Earnings Release and company documents for American State; Data as of December 31, 2011; Cost of deposits as of quarter ended December 31, 2011
th

12
Net Interest Margin
*
Net Interest Margin
*
4.02%
4.06%
3.82%
4.02%
3.99%
3.97%
4.00%
4.24%
4.08%
4.09%
4.20%
3.98%
3.60%
3.70%
3.80%
3.90%
4.00%
4.10%
4.20%
4.30%
1Q09
2Q09
3Q09
4Q09
1Q10
2Q10
3Q10
4Q10
1Q11
2Q11
3Q11
4Q11
Net Interest Margin for 2008 = 3.96% 
Net Interest Margin for 2009 = 4.08%
Net Interest Margin for 2010 = 4.04%
Net Interest Margin for 2011 = 3.98%
* Tax equivalent- annualized

$0
$500
$1,000
$1,500
$2,000
$2,500
$3,000
$3,500
$4,000
2004
2005
2006
2007
2008
2009
2010
4Q10
4Q11
30.00%
35.00%
40.00%
45.00%
50.00%
55.00%
60.00%
65.00%
70.00%
Loans
Loan / Deposit
Ratio
13
Loan Growth
Loan Growth
$ in millions

14
Pro Forma Loan Composition
Pro Forma Loan Composition
Prosperity Bancshares, Inc.
American State Financial Corporation
Pro Forma
Loan Portfolio ($000)
% of Total
Commercial R.E.
1,441,226
$    
38.3%
Commercial
439,854
         
11.7%
Construction
482,140
         
12.8%
1-4 Family Residential
1,007,266
      
26.7%
Consumer
78,187
           
2.1%
Agriculture
170,234
         
4.5%
Home Equity
146,999
         
3.9%
Gross Loans
3,765,906
$    
100.0%
Yield on Loans
5.70%
Loan Portfolio ($000)
% of Total
Commercial R.E.
537,051
$       
44.3%
Commercial
298,219
         
24.6%
Construction
87,575
           
7.2%
1-4 Family Residential
172,364
         
14.2%
Consumer
66,944
           
5.5%
Agriculture
42,466
           
3.5%
Home Equity
7,271
              
0.6%
Gross Loans
1,211,890
$    
100.0%
Yield on Loans
5.24%
Loan Portfolio ($000)
% of Total
Commercial R.E.
1,978,277
$    
39.7%
Commercial
738,073
         
14.8%
Construction
569,715
         
11.4%
1-4 Family Residential
1,179,630
      
23.7%
Consumer
145,131
         
2.9%
Agriculture
212,700
         
4.3%
Home Equity
154,270
         
3.1%
Gross Loans
4,977,796
$    
100.0%
Yield on Loans
5.59%
Home
Equity
3.9%
Agriculture
4.5%
Consumer
2.1%
1-4 Family
Residential
26.7%
Construction
12.8%
Commercial
11.7%
Commercial
R.E.
38.3%
th
Agriculture
3.5%
Consumer
5.5%
1-4 Family
Residential
14.2%
Construction
7.2%
Commercial
24.6%
Commercial
R.E.
44.3%
Home
Equity
0.6%
Agriculture
4.3%
Home
Equity
3.1%
Consumer
2.9%
1-4 Family
Residential
23.7%
Construction
11.4%
Commercial
14.8%
Commercial
R.E.
39.7%
Source:
PB’s
4
Quarter
2012
Earnings
Release
and
company
documents
for
American
State;
Data
as
of
December
31,
2011;
Yield
on
loans
as
of
quarter
ended
December
31,
2011

Asset Quality –
NPA*/ Loans
+ OREO
*
Includes loans past due 90 days and still accruing
Asset Quality –
NPA*/ Loans
+ OREO
*
Includes loans past due 90 days and still accruing
0.32%
2.30%
0.45%
0.48%
0.40%
0.49%
0.05%
0.09%
0.17%
0.13%
0.38%
0.32%
0.36%
0.45%
3.91%
3.63%
0.84%
0.83%
1.18%
1.02%
0.70%
0.97%
2.26%
2.30%
2.95%
3.91%
0.00%
0.50%
1.00%
1.50%
2.00%
2.50%
3.00%
3.50%
4.00%
4.50%
5.00%
2002
2003
2004
2005
2006^
2007^
2008^
2009^
2010^
2011
4Q10^
3Q11^
4Q11^
PRSP NPA*/Loans + OREO
Peer NPA*/Loans + OREO
Source: SNL Financial
Texas Peer Group Includes: CFR, EBTX, FFIN, FBTX, IBOC, MCBI, SBSI, SNBI, SBIB, SBIT, TCBI, TRBS & TXUI
^ SNBI, SBIT, TRBS & TXUI have been acquired and were excluded from 2006 & 2007 and FBTX failed and was excluded from 2008
NOTE:
15

Asset Quality –
NCO/
Average Loans
Asset Quality –
NCO/
Average Loans
0.14%
0.40%
0.23%
0.18%
0.04%
0.03%
0.23%
0.08%
0.41%
0.06%
0.22%
0.04%
0.08%
0.63%
0.32%
0.96%
0.48%
0.13%
0.19%
0.20%
0.19%
0.30%
1.29%
0.54%
0.61%
0.97%
0.00%
0.20%
0.40%
0.60%
0.80%
1.00%
1.20%
1.40%
1.60%
1.80%
2002
2003
2004
2005
2006^
2007^
2008^
2009^
2010^
2011
4Q10^
3Q11^
4Q11^
PRSP NCO / Loans
Peer NCO / Loans
Source: SNL Financial
Texas Peer Group Includes: CFR, EBTX, FFIN, FBTX, IBOC, MCBI, SBSI, SNBI, SBIB, SBIT, TCBI, TRBS & TXUI
^ SNBI, SBIT, TRBS & TXUI have been acquired and were excluded from 2006 & 2007 and FBTX failed and was excluded from 2008
(Annualized)
16

KBW Conference 3/1/12