Guarantee Mortgage - San Francisco, 505 Montgomery

We have helped Bay Area families finance their home purchase, with over $2 billion in loans annually, and we can help you.

Offering a wide range of products and services, Guarantee Mortgage is well prepared to meet every real estate lending need.

We have 22 years under our belt providing world-class client service. Our top priority is to make sure you are presented with all available loan options, so that you can make an informed decision, that’s right for your financial situation.

Guarantee Mortgage NMLS #1850 and CAL-BRE License #01215943


Recommendations (942)

Oct 5, 2018

Nolan Kelly recommends Ken Dean

Sales Manager

Ken took great care of us! He explained everything thoroughly and made us both feel at ease. Have already recommended him to others.
Oct 2, 2018

Tony Belli recommends Foster Weeks

Real Estate Broker

I am a part time real estate broker. I've conducted 5-10 transactions per year for the past 13 years. I've had varied experiences with mortgage brokers. Without question, Foster stands out as the best I've worked with. This particular transaction was a personal home purchase. My wife and I had a very tight schedule, trying to merge two homes into one, and all in time to get kids into a new school. Foster was responsive from the first contact. Within 2 days we had a pre-approval letter and by early the next week we'd identified the lender and locked rates. The transaction was a smooth as any I can remember. Mostly electronic signatures and communication, very convenient. Foster led us every step through the process with clear communication and direction. There were literally no glitches. The loan docs were ready a full week before close, loan was funded on time, close happened on time. I highly recommend Foster and will use him again.
Sep 10, 2018

Margonne Hutchinson recommends James W. Argo

Office Reception

Jim and the team were so helpful, efficient and made this scary process do-able. I am so incredibly glad we went with Jim. He really knows his stuff. They worked so hard tweaking everything just right so we got the best situation for us.
Sep 6, 2018

Bruce Nita recommends Kathy Derangi


Kathy has always gone above and beyond to find the best solution with transparent guidance that only a seasoned and skilled agent can provide. Thanks so much Kathy for helping us through our first home and your continued support in years that come.
Sep 4, 2018

Aaron Aknin recommends Aisling Ferguson

Aisling has helped me with two different transactions - a refinance as well as the purchase of a home. Both transactions were complex because they involved a multi-family dwelling and more than one owner on title. She did a great job both times and I would use her services again for sure.
Sep 3, 2018

Pete recommends Kathy Derangi

Kathy was extremely diligent and responsive. We needed a quick close and Kathy was able to coordinate all aspects of the close in order to achieve the desired outcome.
Aug 11, 2018

David Brant recommends Kathy Derangi

As first-time homebuyers, Kathy was an exceptional mortgage broker for us. She laid out a very clear financing path for us given our budget and down payment, and she was transparent with us on what we would get approved for. Kathy was on top of everything when it came to loan pre-approval, and more importantly the very tight Close of Escrow period. My fiancé and I highly recommend Kathy for any first-time homebuyers in the SF market.
Aug 8, 2018

Wyatt Hunter recommends Aisling Ferguson

She's the best - very clear, very concise, very friendly and very helpful. Made the mortgage process as smooth as possible and was flexible when I had a funding hiccup along the way.
Aug 7, 2018

Claudia Natasia recommends James W. Argo

UX Researcher

Jim was very responsive and knowledgeable. He made the process of purchasing our first home very easy for us. You can always count on him to answer any questions you have immediately. I highly recommend his services.
Aug 1, 2018

Chris recommends Larry Horowitz

08/01/2018 Larry is professional, reliable and went to great lengths to make our loan process run smoothly. He is very attentive to detail, and quickly responded to phone calls and emails. He went out of his way to communicate with our realtor, escrow officer and even the seller when questions needed answering. We have used Larry for multiple real estate transactions and highly recommend his services.
Aug 1, 2018

Carl recommends Larry Horowitz

08/01/2018 I've been working with Larry for over 25 years now, and he has always been helpful and reliable. He went above and beyond the call of duty for this recent transaction. He was creative, patient, and persistent. Not many lenders could have helped me in the way Larry did.
Jul 31, 2018

Anonymous recommends Kathy Derangi

Very helpful and efficient
Jul 31, 2018

Michelle W recommends Aisling Ferguson

As a first time home buyer in the bay area, Aisling made the loan process incredibly easy and painless for me. I have nothing but good things to say about the way she works and her ability to make things happen in a timely and efficient manner. She was highly communicative every step of the way, and I never had to followup with her as she was always following up with me. While extremely busy, she also never failed to leave time for me and reminded me to reach out with questions or concerns even on weekends. I fully endorse working with Aisling and look forward to doing so again in the future.
Jul 30, 2018

Abraham Zachariah recommends Kathy Derangi

Very customer service oriented and efficient
Jul 30, 2018

Robert Mayer recommends Aisling Ferguson

Realtor Associate at Hill & Co San Francisco

I have worked exclusively with Aisling for all my clients mortgage needs for over 20 years. Aisling has consistently under promised and over delivered each and every time I have sent a client to her. Even with the more challenging lending situations, she has always performed with a laser focus on delivering results.
I highly recommend Aisling !
Jul 27, 2018

Cy Berlowitz recommends Aisling Ferguson

"Aisling Ferguson assisted us in obtaining two loans to help us purchase a condo for our daughter in San Francisco. It was a complicated transaction but Aisling sailed through it like like the consumate professional that she is. Besides, she held our hands all the way through the transactions.until its completion. Our daughter is now the proud owner of a San Francisco condo, and we couldn't be happier. Anyone needing assistance with a loan would be fortunate to use Aisling Ferguson.

Sincerely Yours,

Cy Berlowitz
Jul 26, 2018

Laila Zachariah recommends Kathy Derangi

Exceptional!!! The very best experience.
Jul 24, 2018

Procie Sichon recommends Orlando Diaz


Orlando did an excellent job, and worked through challenges faced by retired clients. He responded to my questions even when he was out of town. I felt confident and reassured throughout the process and I strongly recommend him to family and friends.
Jul 11, 2018

Lynn Trinh recommends Aisling Ferguson

My husband and I are beyond happy to have worked with Aisling during our house hunting journey. She's incredibly knowledgeable, responsive and a fantastic problem solver. When there were hiccups along the way, Aisling presented us solutions and help guide us to make informed decisions. We got pre-approved and closed on our house within 8 weeks which to me and my husband, is wildly fast since we are first time homeowners.
Jul 9, 2018

Eduardo campos recommends Guarantee Mortgage

Alberto has been working with my family for quite some time now. He made sure We had the best rates compared to other lenders which was a great help! He made the whole process so easy!! Answered every question I had and always explained everything in detail. I would definitely recommend him to anyone looking to buy a home. He is a great genuine guy, which only interest is to make the whole buying process the least stressful for you. Thank you Alberto for your help!!! Looking forward to work with you in the near future.
Jul 6, 2018

Richard Malott recommends Orlando Diaz

Site Manager

Orlando was able to help us refinance our home under trying circumstances. He was always available for us. I would highly recommend Orlando to anyone looking for help with their refinance.
Jul 4, 2018

Mylene Ardanas recommends Guarantee Mortgage

Accounts Payable Analyst

Working with Alberto R Zamudio was pleasant. Alberto was professional, courteous, patient and thorough answering all our questions. He kept the ball rolling and he kept his promise. We able to closed the escrow within less than 30 days and meet our deadline to our move out date from previous location. An excellent job!!!! I would definitely highly recommend him to all our friends and colleague.
Jul 4, 2018

Chad Zahorchak & Jennifer Kellogg recommends Aisling Ferguson

Executive Integrated Producer

Aisling comes through again! This was our third purchase with her and it only gets better. Very clear and upfront with options to consider that eased our minds from day one. Very fast and thorough, highly recommend.
Jul 2, 2018

Sandy Gandolfo recommends Orlando Diaz


Orlando did a great job for our buyers, everything was easy start to finish!
Jun 26, 2018

Bill Wright recommends James W. Argo


Jim Argo is an experienced professional who can get the job done. He listened to my complicated and unorthodox financing needs and then he and his team figured out how to get those needs met. At the end of the day, that's really what matters. I would also like to commend the thoroughness and professionalism of his team which is critically important in getting lenders to fund a transaction in a highly regulated environment. Good job everyone !

Our Team

  • Aisling Ferguson

    NMLS #280915 Loan Consultant - San Francisco
    NMLS #280915 / 1850 - CA BRE #01225420 / 01215943

  • Orlando Diaz

    Sr. Loan Consultant - San Francisco - Montgomery St.
    NMLS #238849 / 1850 - CA BRE #01475255 / 01215943

  • Foster Weeks

    Loan Originator - San Francisco - Montgomery St.
    NMLS #253370 / 1850 - CA BRE #01383598 / 01215943

  • Kathy Derangi

    Loan Consultant - San Francisco - Montgomery St.
    NMLS #1151839 / 1850

  • Natasha Lovas

    Senior Mortgage Advisor - San Francisco - Montgomery St.
    NMLS #239455 / 1850 - CA BRE #01161948 / 01215943

  • James W. Argo

    Senior Loan Officer - San Francisco - Montgomery St.
    NMLS #257031 / 1850 - CA BRE #00869591 / 01215943

  • Larry Horowitz

    Loan Consultant - San Francisco - Montgomery St.
    NMLS #239001 / 1850 - CA BRE #01003870 / 01215943

  • Robin Patronik

    Senior Loan Officer - San Francisco - Montgomery St.
    NMLS #241087 / 1850 - CA BRE #01347330 / 01215943

  • Allan McAllister

    Loan Consultant - San Francisco - Montgomery St.
    NMLS #280540 / 1850 - CA BRE #01372084 / 01215943

  • Ken Dean

    Loan Consultant - San Francisco - Montgomery St.
    NMLS #237940 / 1850 - CA BRE #0902556 / 01215943

  • Cecelia Tyeskey

    Sr. Mortgage Loan Consultant - San Francisco - Montgomery St
    NMLS #239861 / 1850 - CA BRE #01212004 / 01215943

  • Kevin Casey

    Loan Consultant - San Francisco - Montgomery St.
    NMLS #238192 / 1850 - CA BRE #01178612 / 01215943

  • Risa J. Meyer

    Mortgage Specialist - San Francisco - Montgomery St.
    NMLS #332214 / 1850 - CA BRE #01126851 / 01215943

  • Ming Leong

    Loan Consultant - San Francisco - Montgomery St.
    NMLS # 252471 / 1850 - CA BRE #01369831 / 01215943

  • Bob Siefert

    Senior Vice President - San Francisco - Montgomery St.
    NMLS #55105 / 1850 - CA BRE #00921214 / 01215943

  • Mireille Costandi

    Loan Consultant - San Francisco - Montgomery St.
    NMLS #249322 / 1850 - CA BRE #01132350 / 01215943

  • Amy Lai

    Loan Consultant - San Francisco - Montgomery St.
    NMLS #341535 / 1850 - CA BRE #01795977 / 01215943

  • Paul Rea

    Loan Consultant - San Francisco - Montgomery St.
    NMLS #280163 / 1850 - CA BRE #00856755 / 01215943

  • KC Murphy

    Sr. Loan Consultant - San Francisco - Montgomery St.
    NMLS #255492 / 1850 - CA BRE #1007053 / 01215943

  • Sally Adam

    Loan Consultant - San Francisco - Montgomery St.
    NMLS #245703 / 1850 - CA BRE #01244582 / 01215943

  • Sheila Wood

    Manager/Loan Consultant - San Francisco - Montgomery St.
    NMLS #253742 / 1850 - CA BRE #00824166 / 01215943

  • Fe David

    Loan Consultant - San Francisco - Montgomery St.
    NMLS # 482592 / 1850 - APMC CA BRE #01215943